Let's start with the Yemenite reference. The story that follows says that Simon Peter had forsaken the Christian religion at some time following Jesus' death, and he went off to live in Babylon. However, when he returned on a visit to the land of Israel, he was compelled by the local gentile inhabitants (those who were Christians and who controlled access to the Temple Mount) to remain amongst them in their own country, and not to return to Babylon. They had threatened him by saying that they would prevent Jews from entering the Temple Mount if he would refuse to do so.
Here is the original story as well as the English translation:
והיה בבבל חכם גדול וראש סנהדרין ושמו שמעון כיפה. ולמה נקרא שמו שמעון כיפה שהיה עומד על האבן שנתנבא עליה יחזקאל והוא בנהר כבר והיתה האבן רועשת וצד האבן נענה ואומר בת קול נענה מן השמים לשמעון כיפה כיון ששמעו נצרים כך בבית המקדש ששמעון כיפה משתמש בבת קול ויש בו חכמה עד אין חקר ואין מספר והיו מתקנאין בישראל שאין בישראל כמותו. הכניס הקב"ה בלבו של שמעון כיפה עצה שיעלה לירושלם. כיון שעלה לירושלם והתפלל שם בחג הסכות נתקבצו אגמוטס והישיש הגדול של נצרים ובאו אצל שמעון כיפה להר הזיתים ביום הושענא. כיון שראו חכמתו אמרו נתיעץ ביחד ולא נניח כמות זה שיהיה בישראל. החזיקו בידו ואמרו לו לא נניחך שתחזור לבבל ותהיה עם היהודים אלא חזור עמנו ותהיה נצרי כמותינו ואנחנו נעשך ראש לכל הנצרים. אמר להם לא אניח דין ישראל. אמרו לו אם לא תחזור לדין נצרים אנו נהרוג אותך ונהרוג כל יהודי שיכנס למקדש. כשראו כך נתקבצו ונתחננו לו ואמרו לו אין עליך בזה הדבר כלום אשמה ועון. חזור עמהן ותהיה לישראל מושיע ותעשה ברוב חכמתך. כיון שראה שהגזירה קשה על ישראל חזר עם הנצרים ואמר להם אני חוזר לדינכם על מנת שלא תכו ולא תהרגו יהודי הבא בבית המקדש ולא תמנעום מן הזיתים. קבל הישיש עם שאר הנצרים אלו התנאים ושלא ימנעו יהודי מבית המקדש. ועוד התנה עליהם שיבנו לו מגדל גבוה ויכנס בתוכו ולא יאכל בעולם לא בשר ולא דבר אחר אלא לחם ומים לבד ואני אהיה מוריד (לרם) [לכם] קופה בחבל ותנו לי לחם בתוכה וכל כך עשה שלא יטמא במאכלם ולא ישתחוה לצלם. לאחר כך עשה סדור תפלות קרובוצות לכל השנה ויוצרות ומוספין על שמו כשם שעשה ר' אליעזר ביר' קילר. ושלח וקיבץ זקני ישראל וא"ל בבקשה מכם שתקחו ממני זה הסידור ותשלחוהו לבבל לראשי ישיבות אם ייטב בעיניהם ילמדוהו לחזנים ויתפללו בו כדי שיזכר שמי עמהם. שלחו אותו לר' נתן דצוציתא שהיה ראש גלות והראהו לראשי ישיבות ולסנהדרין ואמרו טוב הוא. ואמרו לזקנים קחו אותו ולמדוהו כל מי שרוצה יתפלל בו עד היום הזה. והיו מתפללין בו כל שבת וזה שמעון כיפה הוא שקורין אותו הנשטורין פטרוס. זה השלמת מעשה ישו. של ישו בן פנדירא דכפר באלהא רבא ואטעי עלמא בתרוי.
Now there was in Babylon a great wise man and the head of the Sanhedrin, and his name was Simon Caipha. Now why was he called Simon Caipha? Because he used to stand upon the rock which Ezekiel prophesied upon when he was on the River Chabar, and the stone would shake [as if there was an earth quake] and one side of the stone would answer [him] and they would say the 'bath kol' (a heavenly voice) had answered Simon Caipha out of heaven. When the Nazoraeans heard this in the Temple precincts that Simon Peter (lit. Caipha) had recourse to the 'bath kol' (a heavenly voice), and that he was endowed with wisdom beyond compare, they became jealous of Israel, for there was no one in Israel like unto him. The Holy One, blessed be He, had put within the heart of Simon Caipha counsel to go up to Jerusalem. When he had come up to Jerusalem and prayed there on the Feast of Tabernacles (Heb. Hag Hasukkoth), there came together Agmost and the great elder of the Nazoraeans, and went unto Simon Caipha to the Mount of Olives during [the last day of the feast, known as] Hoshanna. When they had seen his wisdom, they said unto him: Let us take counsel together, for we will not let aught that is like unto this remain amongst [the people of] Israel [which live abroad]. They held fast his hand and said to him: We will not let you return to Babylon and to be with the Jews [there]. Rather, come back unto us and be a Nazoraean like us, and we will make you the chief of all the Nazoraeans. He said unto them: I shall not leave the religion of Israel. They said to him: If you do not return to the religion of the Nazoraeans, we will kill you and will kill every Jew that enters the Temple precincts. When they [of Israel] saw that things came to that, they gathered themselves together and pleaded with him, saying: You have nothing to fear about this matter, neither guilt nor iniquity. Go back to them and be for Israel as a saver of life, and do according to thy abundant wisdom. When he saw that the decree was hard upon Israel, he went back to the Nazoraeans and said to them: I am coming back to your religion on the condition that you do not smite or kill a single Jew that comes to the Temple precincts, neither hold-back from them their olives. The elder accepted of his conditions, as well as the other Nazoraeans, that they not prevent a Jew from entering the Temple precincts. He also made with them another stipulation that they should build for him a high tower, into which he would go, and that he would not eat in this world flesh or anything else besides bread and water alone, [saying] that I will lower down for you a basket by a rope and put therein for me bread. Now he did all this so that he might not be defiled by their foods, neither bow down to a graven image.
Afterwards, he made a Prayer Book (siddur tefillloth) of liturgies for the entire year, as well as the 'yotzer' verses and 'Musaf' prayers, under [the acrostics] of his name, just as Eleazar the son of Rabbi Killir did, and sent and gathered together the elders of Israel and said to them: I beseech thee that you take from me this Prayer Book (Siddur), and send it to Babylon, to the heads of the academies there. If it should be pleasing in their sight, let them teach it to their [synagogue] cantors, and pray in it, so that my name might be remembered amongst them. They then sent it to Rabbi Nathan of Susitha, who was the Exilarch [at that time], and he showed it to the heads of the academies and to the Sanhedrin (the council or assembly of judges), and they said that it was good. They then said to the elders: Take it and learn it. Anyone who wishes let him pray in it. [And thus we have it] to this very day. Now they would pray in it each Sabbath day. Now this Simon Caipha, he it is that is called by the Nestorians 'Peter' (Petros)…
It is rarely reported there is persistent tradition which goes back as far as Simḥah b. Samuel, an outstanding student of Rashi that the head of Christianity - in this case St. Peter -was the author of this prayer Nishmat kol cha'i "the Soul of Every Living Thing." It is very difficult to explain.
The Nishmat is recited as part of the Shacharit (morning) service on Sabbaths and festivals immediately following 'Song at the Sea'. It is also said at the Passover Seder. The first paragraph was known in Mishnaic times, the second was composed during the talmudic period and the concluding part was added during the geonic period.
The connection with the Song of the Sea is interesting as it brings us back to the possibility that the prayer was somehow originally connected with Mark - the founder of Alexandrian Christianity - and then at a later date after the reference no longer made sense was associated with Peter by European Jewry.
Here is a rough translation of the original prayer which reads:
Nishmat kol chai t'vareich et shimcha Hashem Elokeinu, v'ruach kol basar t'faeir utromeim zichr'cha malkeinu tamid
The soul of every living being shall bless Your Name, Hashem, our God; the spirit of all flesh shall always glorify and exalt Your remembrance, our King.
Min ha-olam v'ad ha-olam atah Kel, umi-baladecha ein lanu melech goel u-moshia
From this world to the World to Come, You are God, and other than You we have no king, redeemer or savior.
Podeh u-matzil umfarneis umracheim b'chol et tzarah v'tzukah, ein lanu melech ela atah
Liberator, Rescuer, Sustainer and Merciful One in ever time of distress and anguish, we have no king but You!
Elokei harishonim v'ha-acharonim, Elokah kol b'riyot, adon kol toladot, ham'hulal b'rov hatishbachot, ham'naheg olamo b'chesed uvri-yotav b'rachamim
God of the first and of the last, God of all creatures, Master of all generations, Who is extolled through a multitude of praises, Who guides His world with kindness and His creatures with mercy.
VaHashem lo yanum v'lo yishan
Hashem neither slumbers nor sleeps.
Ham'oreir y'sheinim, v'hameikitz nirdamim, v'hameisiach il'mim, v'hamatir asurim, v'hasomeich nof'lim, v'hazokeif k'fufim, Lecha l'vad'cha anachnu modim
He Who rouses the sleepers, Who awakens the slumbers, Who makes the mute speak, Who releases the bound, Who supports the fallen, and Who straightens the bent - to You alone we give thanks.
Ilu finu molei shirah ka-yom, ulshoneinu rinah kahamon galaiv, v'siftoteinu shevach k'merchevei raki'a, v'eineinu m'irot ka-shemesh v'cha-yareyach, v'yadeinu f'rusot k'nishrei shamayim, v'ragleinu kalot ka-ayalot, ein anachnu maspikim l'hodot lecha Hashem Elokeinu Veilokei avoteinu, ulvareich et sh'mecha al achat mei-olef elef alfei alafim v'ribei r'vavot p'amim hatovot she-asita im avoteinu v'imanu
Were our mouth as full of song as the sea, and our tongue as full of joyous song as its multitude of waves, and our lips as full of praise as the breadth of the heavens, and our eyes as brilliant as the sun and the moon, and our hands as outspread as eagles of the sky and our feet as swift as hinds - we still could not thank You sufficiently Hashem, our God, and God of our forefathers, and to bless Your Name for even one of the thousand thousand, thousands of thousands and myriad myriads of favors that You performed for our ancestors and for us.
Mimitzrayim g'altanu Hashem Elokeinu, u-mibeit avodim p'ditanu
You redeemed us from Egypt, Hashem, our God, and liberated us from the house of bondage.
B'ra-av zantanu, uvsava kilkaltanu, meicherev hitzaltanu, u-midever milat-tanu, u-meichalayim raim v'ne-emanim dilitanu
In famine You nourished us and in plenty You sustained us, from Sword You saved us; from plague You let us escape; and from severe and enduring diseases You spared us.
Ad heina azarunu rachamecha, v'lo azavunu chasadecha V'al tit'sheinu Hashem Elokeinu lanetzach
Until now Your mercy has helped us, and Your kindness has not forsaken us. Do not abandon us, Hashem, our God, forever.
Al kein eivarim shepilagta banu, v'ruach unshama shenafachta b'apeinu, v'lashon asher samta b'finu, hein heim yodu vivar'chu vishab'chu vifa-aru virom'mu v'ya-aritzu v'yakdishu v'yamlichu et shimcha malkeinu
Therefore, the organs that You set within us, and the spirit and soul that You breathed into our nostrils, and the tongue that You placed in our mouth - all of them shall thank and bless and praise and glorify and exalt and revere and sanctify and declare the sovereignty of your Name, our King.
Ki chol peh lecha tishova, v'chol berech lecha tichra, v'chol komah l'fanecha tishtachaveh, v'chol l'vavot yiraucha, v'chol kerev uchlayot y'zam'ru lishmecha, kadavar shekatuv: Kol atzmotai tomarnah, Hashem mi chomocha, matzil ani meichazak mimenu, v'ani v'evyon migoz'lo
For ever mouth shall offer thanks to You; every tongue shall vow allegiance to You; every knee shall bend to You; every erect spine shall prostrate itself before You; all hearts shall fear You, and all innermost feelings and thoughts shall sing praises to Your name, as it is written: "All my bones shall say: 'Hashem, who is like You?' You save the poor man from one stronger than he, the poor and destitute from one who would rob him."
Mi yidmeh lach, u-mi yishveh lach, u-mi ya-arach
Who is like unto You? Who is equal to You? who can be compared to You?
Ha-Kel hagadol hagibor v'hanora, Kel Elyon, konei shamayim va-aretz
O great, mighty, and awesome God, the supreme God, Creator of heaven and earth.
N'halelcha unshabeichacha unfa-ercha unvareich et sheim kadshecha, ka-amur: L'David, bar-chi nafshi et Hashem, v'chol k'ravai et sheim kadsho
We shall laud, praise, and glorify You and bless Your holy Name, as it is said: "of David: Bless Hashem, O my soul, and let all my innermost being bless His holy Name!"
Now here is another interesting thing. When the prayer is referenced in the Talmud it is either identified as a prayer of thanksgiving for the rainfall that follows a drought or that it originally developed as an embellishment to Hallel said at the Passover seder. This view is based on the Talmudic discussion that calls for reciting Nishmat after Hallel over the fourth cup of wine. The Mishnah reads:
THEY FILLED THE THIRD CUP FOR HIM. HE THEN RECITES GRACE AFTER MEALS. OVER THE FOURTH [CUP] HE CONCLUDES THE HALLEL, AND RECITES THE GRACE OF SONG. BETWEEN THESE CUPS [i.e. the first, second and third] HE MAY DRINK IF HE WISHES; BETWEEN THE THIRD AND THE FOURTH HE MAY NOT DRINK.
And then the Gemara explains the what 'reciting the grace of song' means as follows:
R. Hanan said to Raba: This proves that Grace after meals requires a cup [of wine]. Said he to him: Our Rabbis instituted four cups as symbolizing freedom: let us perform a religious act with each.
Hence Grace is recited over the third. The Gemara concludes with a reference to our prayer:
What is ‘THE GRACE OF SONG’? Rab Judah said: ‘They shall praise Thee, O Hashem our God’; while R. Johanan said: ‘The breath of a living [etc.]’
It is no small witness then that R. Johanan b. Nappaha the original codifier of the Talmud thinks that the prayer is recited over the fourth cup. Yet what should we make of the fact that so many sources identify this 'embellishment' as having originated with the head of Christianity?
So let's develop our theory that this developed as an 'embellishment' of the traditional Passover seder. A number of scholars have already noted that the rituals associated with the heretic 'Mark' in Irenaeus had a similar origin. So we read:
Pretending to consecrate cups mixed with wine, and protracting to great length the word of invocation, he contrives to give them a purple and reddish colour, so that Grace, who is one of those that are superior to all things, should be thought to drop her own blood into that cup through means of his invocation, and that thus those who are present should be led to rejoice to taste of that cup, in order that, by so doing, the Charis, who is set forth by this magician, may also flow into them. Again, handing mixed cups to the women, he bids them consecrate these in his presence. When this has been done, he himself produces another cup of much larger size than that which the deluded woman has consecrated,) and pouting from the smaller one consecrated by the woman into that which has been brought forward by himself, he at the same time pronounces these words: "May that Chaffs who is before all things, and who transcends all knowledge and speech, fill thine inner man, and multiply in thee her own knowledge, by sowing the grain of mustard seed in thee as in good soil." Repeating certain other like words, and thus goading on the wretched woman [to madness], he then appears a worker of wonders when the large cup is seen to have been filled out of the small one, so as even to overflow by what has been obtained from it. By accomplishing several other similar things, he has completely deceived many, and drawn them away after him.[Irenaeus i.13.2]
Hippolytus's version of the ritual involving many cups is as follows:
This (heretic) alleged that there resided in him the mightiest power from invisible and unnameable places. And very often, taking the Cup, as if offering up the Eucharistic prayer, and prolonging to a greater length than usual the word of invocation, he would cause the appearance of a purple, and sometimes of a red mixture, so that his dupes imagined that a certain Grace descended and communicated to the potion a blood-red potency ... And this (Marcus), infusing (the aforesaid) mixture into a smaller cup, was in the habit of delivering it to a woman to offer up the Eucharistic prayer, while he himself stood by, and held (in his hand) another empty (chalice) larger than that. And after his female dupe had pronounced the sentence of Consecration, having received (the cup from her), he proceeded to infuse (its contents) into the larger (chalice), and, pouring them frequently from one cup to the other, was accustomed at the same time to utter the following invocation: "Grant that the inconceivable and ineffable Grace which existed prior to the universe, may fill thine inner man, and make to abound in thee the knowledge of this (grace), as She disseminates the seed of the mustard-tree upon the good soil." And simultaneously pronouncing some such words as these, and astonishing both his female dupe and those that are present, he was regarded as one performing a miracle; while the larger was being filled from the smaller chalice, in such a way as that (the contents), being superabundant, flowed over ... but they, horrified at the same time, and eager (to taste the contents of the cup), proceeded to drink (the mixture), as if it were something divine, and devised by the Deity.[Ref.vi.35,36]
I am not sure if my solution to this historical curiosity is any better than what they Jewish sources themselves say. Rabbi Simcha the disciple of Rashi says in his Mahzor Vitri, in the section on the Passover Haggadah where he writes about Birkas Hashir, referencesw a common belief in his days that Simon Peter had written the Nishmath Kol Hai. Simcha derides Simon Peter in harsh terms by calling him "Peter Hamor" – which is a play on words. Peter, in Greek, means "rock." "Peter Hamor," in Hebrew, means "the firstborn of a donkey." Rabbi Simcha goes on to say that anyone who says that Simon Peter wrote "Nishmath Kol Hai" will, when the Temple is rebuilt, have to bring for his atonement a fat sin-offering.
