"Moses wrote the section of Bilaam"

So says TB Bava Batra 14b:

 ומי כתבן משה כתב ספרו ופרשת בלעם ואיוב

 Who wrote them? Moses wrote his own book and the portion of Balaam and Job.

 This is an altogether strange passage, and it is difficult to ascertain whether this refers to an editorial process or the actual composition. Certainly the books that are attributed to the Men of the Great Assembly in the next passage seem to be referring to the final redaction of those books, such as the 12 Prophets, and not their actual composition. It says David wrote Psalms, yet it also says he included other works in it.

Arnold Ehrlich, the 19th century koifer, suggests that Moses used a book available at that time and wrote it into his Torah. Here are his words on Numbers 24:24, as a footnote to his suggestion that Balaam's prophecies were very old, and the involvement of Balak was written in later for various reasons. For Balaam's nation and Balak's nation are adversaries - why would Balak go to Balaam, an enemy?

והוא שאמרו הראשונים משה כתב ספרו ופרשת בלעם (בבא בתרא י״ד ע״ב) הרי שלפי הקבלה פרשת בלעם כתובה בתורה מעל ספר אחר; שאם לא כן מה ספרו ופרשת בלעם שאמרו והלא פרשת בלעם מן ספרו ?ורק על פי מה שאמרתי יפול במאמרם הלשון הזה.

 And that is what the early sages said, Moses wrote his book and the portion of Balaam (Bava Batra 14b), for it was a tradition that the portion of Balaam written in the Torah came from a different book. If this weren't so, what does "his book and the portion of Balaam" mean? Isn't the "portion of Balaam" part of "his book"? It is only according to what I have said that their statement's phraseology can be understood.

R. Abraham Joshua Heschel suggests the same thing in his "תורה מן השמים באספקלריה של הדורות", page 455.

However, the parallel line in Yerushalmi Sotah 5:6 indicates to me something very different:

משה כתב חמשה ספרי תורה וחזר וכתב פרשת בלק ובלעם וכתב ספרו של איוב

Moses wrote the five books of the Torah, and then went back and wrote the portion of Balak and Bilaam, and he wrote his book of Job.

This indicates that the meaning of the line is that he wrote it out of order, not that it came from a different source.

Interestingly, the version of Yerushalmi I have has an alternate version of this line that says that "Moses wrote the fifth book, and then went back and wrote the portion of Balak and Bilaam." Meaning, the fifth book is Deuteronomy, and not all of the Torah. Indeed, some versions of the Sifre on Deuteronomy explicitly state that "Moses wrote his book" means Deuteronomy. As we know, Deuteronomy is widely recognized in Chazal as having been originally generated by Moses with God's approval, and so it might be saying that Balak and Bilaam was also originally generated by Moses and included with God's approval.

Rav Menachem Mendel Kasher actually suggests the opposite, that since people might suspect that it was written by Moses himself without prophecy, the emphasis was that both were written with prophecy, an idea he got from the Chatam Sofer, Shu"t YD 356, who noted that unlike the rest of the Torah that could be handed down as tradition that everyone witnessed, nobody could pass down the story of Bilaam. Yet, anyone who denies its place in Scripture is a koifer, says the Chatam Sofer. So the Talmud wanted to emphasize its place in Scripture.

But actually, the same idea is already found in the Ralbag at the end of Parshat Balak:

וקודם שנזכור התועלות המגיעות ממנה נזכיר ספק אחד בענין זאת הפרשה, והוא: איך נזכרה נבואת בלעם וסיפור דברי בל עימו בתורה? כל שכן שיתחזק זה הספק מצד מה שמצאנו שכבר היה בלעם קוסם

ונֹאמר שכבר נזכרה זאת הפרשה בזה המקום מצד התועלות המגיעות ממנה, כי כבר יתבאר ממנה עוצם השגחת ה' יתעלה על ישראל, כמו שביארנו. ולזה אמר הנביא: 'עמי זכר נא מה יעץ בלק מלך מואב, ומה ענה אֹתו בלעם בן בעור מן השטים עד הגלגל' (מיכה ו, ה). ובה גם כן תועלת להודיע מה היתה הסיבה בזניית ישראל אחר העריות ואחר עבודה זרה, ולמה נצטוו ישראל להרוג את המדינים. וראוי שתדע שאלו הסיפורים מבלק ובלעם ידעם כולם משה רבינו ע"ה מפי הגבורה, ולא נודעו לו על צד הפרסום, כי בזולת זה לא היה ראוי שיִכָּתבו בתורה. הנה כמו שהגיד משה מפי הגבורה דבר הסיפורים שבאו בספר בראשית, כן הגיד זה הסיפור אשר בזה המקום מפי הגבורה. ומזה האופן נתאחדו הסיפורים עם המצוות בתורה, לפי שהם כולם מכוונים להביא אל השלמות האנושי — הנמשכים לדברי התורה. ואל זה כיוונו ז"ל באומרם שמשה כתב פרשת בלעם.

Why does the Yerushalmi say it as "he went back"? Interestingly Rav Kasher points out that there was a prominent rabbi, the Rashban, Rav Shlomo Tzvi Shick, who suggests that the meaning is that Moses wrote it, but it was only included into the Torah proper after the people of Israel already settled the land of Israel. Rav Kasher doesn't accept this and is upset Rabbi Shick would just ignore the 8th principle of Maimonides. Rav Kasher instead suggests it is in accordance to the opinion who says the Torah was written a scroll (megillah) at a time, piecemeal. So it just means that after all the other scrolls were written, did Moses write the section of Bilaam.

It appears as if most were unaware of this passage in the Yerushalmi, or ignored this simple meaning. Korban HaEda just quotes Rashi from the Bavli, who wrote:

ופרשת בלעם. נבואתו ומשליו אף על פי שאינן צורכי משה ותורתו וסדר מעשיו:

And the portion of Balaam: His prophecies and proverbs, even though they aren't [about] Moses' needs, his Torah [laws], and the stories of his actions.

I'm reading this in two very different ways.

Either Rashi is saying that the hava amina is that Moses did not compose it, because its not about him or his laws. Or Rashi is saying that he didn't have to include it in the editorial process, since it isn't about him or his laws, so one would question why he included it in the Torah at all. Both have different answers, implied. For the first, the Talmud is teaching us that Moses did indeed write it, nevertheless. Why? Rashi doesn't go that far here. For the second, the Talmud is teaching us that Moses included it nevertheless. Again, no clue as to why.

Rabbeinu Gershom, on the page, is also perplexing:

ופרשת בלעם. אע"ג דבלעם גופיה הוה נביא

And the portion of Balaam: Even though Balaam himself was a prophet.

This one seems to be clearer, and it is an outright rejection of the conclusion Ehrlich came to about this passage in the Talmud. Rabbeinu Gershom is saying the hava amina is that Balaam would have written his own prophecy, because he was a prophet. The Talmud therefore teaches us that Moses composed this portion himself.

Still, I could see someone reading this  line as saying that Moses included this portion, even though the portion was written by another prophet, Balaam.

The Ritv"a has the most interesting answer I have found in the rishonim. He suggests that a book of Balaam's prophecies existed in the time of Chazal, and that is the book they refer to when they say Moses wrote it. For him, it does not refer to any portion of the Torah. Here are his words, written in his Chiddusim to Bava Batra 15a:

והא דאמרינן לעיל במשה שכתב ספרו ופרשת בלעם נראין דברי האומרים שאין זו פרשת בלעם שכתובה בתורה דההיא הקב"ה כתבה כשאר התורה אלא פרשה בפני עצמה היא שכתב והאריך בה יותר והיתה מצויה להם 

That which we said earlier that Moses wrote his book and the portion of Balaam, it seems [correct] according to those that say that this is not the portion of Balaam written in the Torah, for that was written by God, like the rest of the Torah, rather this refers to a separate portion that [Moses] wrote, which was much lengthier [than the portion in the Torah], and they possessed it.

Perhaps a source to bolster this idea is the line in Sanhedrin 106b that there existed a certain "notebook" of Bilaam, which seems to indicate that like the Chronicles of Moses and other such books, there was also a Chronicle of Bilaam:

דידי חזי לי פנקסיה דבלעם והוה כתיב ביה בר תלתין ותלת שנין בלעם חגירא כד קטיל יתיה פנחס ליסטאה

I personally have seen Balaam's Chronicle, in which it is stated, 'Balaam the lame was thirty years old when Phinehas the Robber killed him.' 

Ibn Shuib writes similarly in his derashot to Parashat Balak:

ואין ספק כי הכתובים קצרו ענין בלעם ונבואותיו לישראל לפי שעה, וגם קצר הכתוב בענין חכמת קסמים כמו שקיצר בענייני ע"ז של דור אנוש שלא סיפר בו הכתוב כלל, וחבר בו אברה' אבינו ע"ה ספר שהיו בו ת' פרקים כמו שאמרינן ע"ז דאברהם אבינו ארבע מאה פרקי הוו. ובכאן קצר ענין בלעם... ונראה מדעת רבותינו ז"ל כי משה רבינו ע"ה חבר ספר לבד מה שהוא כתוב בתורה, והיה שם סיפור פרשת בלעם כמו שאמר, משה כתב ספרו ופרשת בלעם וספר איוב, ורחוק הוא שנפרש פרשת בלעם על הפרשה הזאת הכתובה בתורה כי בכלל ספרו היא והיא מכלל התורה, אבל היה ספר בפני עצמו ונאבד כמו שנאבדו ספרים אחרים מכלל ארבעה ועשרים ספרים המקודשי' ובכאן בתורה ספר הענין בקוצר.

Undoubtedly, Scripture curtailed the story of Balaam and his prophecies for the Jews according to the time, and it also curtailed the topic of witchcraft, like it curtailed the topic of idolatry in the generation of Enosh which is not described in Scripture at all. And Abraham our father, peace be unto him, wrote a book of 400 chapters about it, as we say, (Avodah Zara 14b) "The idolatry of Abraham contained 400 chapters." And here, the topic of Balaam is curtailed... And it seems [to be] of the opinion of our sages, may their memory be a blessing, that Moses our teacher, peace be unto him, wrote a book apart from that which is written in the Torah, and the name of that book was "Parshat Bilaam", as is said, "Moses wrote his book, Parshat Bilaam, and the book of Job. And far-fetched is the interpretation that "Parshat Bilaam" refers to the portion that is written in the Torah, for that is included in "his book", both included in the Torah. Rather it was a book unto its own, and it was lost, just like other books were lost from the 24 holy books [of Tanach], and here the Torah tells it over in an abridged form.

Ibn Shuib refers to several midrashim that I am not aware of, so explanations of some of this will have to wait.

If the Ritv"a and Ibn Shuib are correct, they may have been referring to this prophecy and others:

Deir Alla inscription: 

McCarter's translation and reconstruction of the text:

(1) [VACAT] The sa]ying[s of Bala]am, [son of Be]or, the man who was a seer of the gods. Lo! Gods came to him in the night [and spoke to] him (2) according to these w[ord]s. Then they said to [Bala]am, son of Beor, thus: Let someone make a [ ] hearafter, so that [what] you have hea[rd may be se]en!" (3) And Balaam rose in the morning [ ] right hand [ ] and could not [eat] and wept (4) aloud. Then his people came in to him [and said] to Balaam, son of Beor, "Do you fast? [ ] Do you weep?" And he (5) said to them, "Si[t] do]wn! I shall inform you what the Shad[dayin have done]. Now come, see the deeds of the g[o]ds!. The g[o]ds have gathered (6) and the Shaddayin have taken their places in the assembly and said to Sh[ , thus:] 'Sew the skies shut with your thick cloud! There let there be darkness and no (7) perpetual shining and n[o] radiance! For you will put a sea[l upon the thick] cloud of darkness and you will not remove it forever! For the swift has (8) reproached the eagle, the voice of vultures resounds. The st[ork has ] the young of the NHS-bird and ripped up the chicks of the heron. The swallow has belittled (9) the dove, and the sparrow [ ] and [ ] the staff. Instead of ewes the stick is driven along. Hares have eaten (10) [ ]. Freemen [] have drunk wine, and hyenas have listened to instruction. The whelps of the (11) f[ox] laughs at wise men, and the poor woman has mixed myrhh, and the priestess (12) [ ] to the one who wears a girdle of threads. The esteemed esteems and the esteemer is es[teemed. ] and everyone has seen those things that decree offspring and young. (15) [ ] to the leopard. The piglet has chased the young (16) [of] those who are girded and the eye ....'"

And in Rav Yaakov Kaminetzky's Emet LeYaakov, beginning of Parshat Matot, he theorizes that all prophets filtered their prophecies through their personalities and psychology, which was not true for Moses, who did not have any filtering process - it was literally the word of God. This is what made Moses special as a prophet. And we know that Bilaam was seen as Moses' equal in prophecy - the Sifre end of Vezot HaBeracha says this explitly.

If so, says Rav Yaakov, Bilaam's story and prophecy did not come from Moses - it came from Bilaam, which came unfiltered from God. If so, he states, all Moses did was take Bilaam's story and put it in the Torah.

One last note, an interesting suggestion by the Sefer Megaleh Amukot Parshat Vatechanan 118 is that "the portion of Balaam" refers to the 18 verses in Joshua that speak of the war with Midian and Balaam's death.

And I'm also finding that Rav Tzadok MLubin understands this passage as meaning that the portion of Balaam did not find expression from the Godhead within Moses' brain, unlike the rest of the Torah, so it specifies he wrote it. What this means is that the words of Balaam's prophecy did not come from Moses himself. Indeed, at least one way of reading Rashi is like that, and perhaps Rabbeinu Gershom. Maharil Diskin does ask on Rashi how he could go against the passage in Chelek that states that one loses their portion for claiming even one word does not come from Moses. First, its not necesarily a question if Rashi only speaks of hava aminas. But secondly, the line in the gemara is really about Moses coming up with it on his own, and ostensibly Rashi believes Balaam's prophecy came from God, so its still valid to go in the book. Maharil Diskin also disagrees with the Ritva for stating that it refers to a compeletely different book, because it seems like all the books mentioned are in the canon, and this book is not. However, if you see above, Ibn Shuib actually answers that critique by stating that it was part of the canon, along with many other books that were lost!