...It is reported about Hillel the Elder that every day he used to work and earn one tropaic, half of which he would give to the watchman at the house of study; the other half he used on food for himself and the members of his household. One day he was unable to earn anything, so the watchman at the house of study did not let him in. He then climbed [to the roof] and hung on, sitting over the opening of the skylight, so that he could hear the words of the living God from the mouths of Shemaiah and Avtalion. It is said that the was a Sabbath eve in the winter solstice, and snow came down on him from heaven. When the dawn rose, Shemaiah said to Avtalion, "Brother Avtalion, every day this house is bright with light, but today it is dark. Is the day cloudy?" When they looked up, they saw the figure of a man in the skylight. They climbed to the roof and found Hillel, covered with three cubits of snow. They removed the snow from him, bathed and anointed him, and, as they seated him in front of an open fire, they said, "This man deserves to have the Sabbath profaned on his behalf."...

(trans. William G. Braude: The Book of Legends (Bialik & Ravnitzky), p. 204

There was another incident involving one gentile who came before Shammai and said toShammai: Convert me on condition that you teach me the entire Torah while I am standing on one foot.Shammaipushed him away with the builder’s cubit in his hand. This was a common measuring stick and Shammai was a builder by trade.

The same gentile came before Hillel. He converted him and said to him: That which is hateful to you do not do to another; that is the entire Torah, and the rest is its interpretation. Go study.

[And raise up many students.] For the House of Shammai, say: One should teach only a person who is wise, humble, of good pedigree, and rich.

But the House of Hillel say: Teach everyone, for there were many sinners in Israel, and they were brought close to Torah study, and they came out righteous, kind, and proper.

For on one occasion the Sages were reclining in the upper story of the house of Gurya in Jericho. A Divine Voice from Heaven was issued to them, and it said: There is one person among you for whom it is fitting that the Divine Presence should rest upon him as a prophet, but his generation is not fit for it; they do not deserve to have a prophet among them. The Sages present directed their gaze to Hillel the Elder. And when he died, they eulogized him in the following manner: Alas pious one, alas humble one, student of Ezra.

Rebbi Joshua from Ono stated: The students of the House of Shammai were standing downstairs and killing the students of the House of Hillel. It was stated, six of them went up; the rest were standing around them with swords and lances.

A history of the composition of the Mishnah and Talmud by Sherira Gaon, leader of the yeshiva of Pumbedita (in current-day Iraq) in 987 CE.

(5) When the Temple stood, each of the rabbis would teach his students the explanations of the Torah, Mishnah, and Talmud...as was appropriate. Knowledge was widespread...

When Shammai and Hillel came, they differed in only three instances...

Once the Temple was destroyed (70 CE), the students went to Beitar and then Beitar was destroyed and the rabbis scattered in all directions.

(DR translation)

“Due to the upheavals, and persecutions, and disturbances that prevailed at that time, the students were unable to properly serve their teachers and there was a proliferation of disputes [Hebrew: מחלוקת/machloket]. (Epistle of Rabbi Sherira Gaon, p. 10)”.Binyamin Lau, The Sages, vol. I, p. 244.

[Partially parallel to Tosefta Hagigah 2:9.]

The Gemara poses a question: But do we adopt the respective stringencies of two authorities who disagree on a series of issues? Wasn’t it taught in a baraita: The halakha is always in accordance with the opinion of Beit Hillel, but one who wishes to act in accordance with the opinion of Beit Shammai may do so, and one who wishes to act in accordance with the opinion of Beit Hillel may do so. If he wishes to adopt both the leniencies of Beit Shammai and also the leniencies of Beit Hillel, he is a wicked person. And if he wishes to adopt both the stringencies of Beit Shammai and also the stringencies of Beit Hillel, with regard to him the verse states: “The fool walks in darkness” (Ecclesiastes 2:14). Rather, he should act either in accordance with Beit Shammai, following both their leniencies and their stringencies, or in accordance with Beit Hillel, following both their leniencies and their stringencies.

(17) Every dispute that is for the sake of Heaven, will in the end endure; But one that is not for the sake of Heaven, will not endure. Which is the controversy that is for the sake of Heaven? Such was the controversy of Hillel and Shammai. And which is the controversy that is not for the sake of Heaven? Such was the controversy of Korah and all his congregation.

(14) He [=Hillel] used to say:

If I am not for myself, who is for me?

But if I am for my own self [only], what am I?

And if not now, when?

It is taught in [a baraita]: They said about Hillel the Elder that when he was rejoicing at the Celebration of the Place of the Drawing of the Water he said this: If I am here, everyone is here; and if I am not here, who is here? In other words, one must consider himself as the one upon whom it is incumbent to fulfill obligations, and he must not rely on others to do so.

"Guarding the Tongue," ethical teachings of Rabbi Israel Meir Kagan (known as the "Chafetz Chaim"), Poland, 1865-1875

In Avot 1:13 [=1.14] we find that Hillel used to say: "If I am not for myself, who will be for me, etc." This apothegm is highly comprehensive. Its plain meaning relates to zeal in the service of the Lord, saying: "If one does not bestir oneself while one is yet alive and while one still has strength, who can help one?" As Scripture states (Koheleth 9:10): "All that your hand finds to do, in your strength do it" — "in your strength," specifically. We have already expatiated upon this elsewhere. For one can depend but very little upon one's children, and one's principal (task) is to prepare "provender for one's destined abode." And it is in this regard that Hillel says plainly: If a man himself does not benefit his soul, who can do it for him?

Chasidic Teachings of Yaakov Yosef of Polonne, 1780. The first Hasidic book ever printed.

(103). And this is the elegance of Hillel’s phrasing, “If I am not for myself, who is for me, etc.” For this is not the phrasing of a question, as is the popular understanding. Rather, it is a statement:

If I am not for myself, meaning if the prayer, which is called "I", as is well-known, is not for me, meaning for my own benefit, but rather as if it is the Divine Presence that is pleading and praying from the Holy One, blessed be He – that is [for] the unification of the Holy One, blessed be He, and the Divine Presence – then Who [Mi] is for me.

For there is a trait that is called Who, which is Understanding [Binah], which is called the living God, and that is the life of the King, from which there is life. And since he has connected Kingship [Malkhut, which is the diving presence], to the Holy One, blessed be He, which is life, then minds from Understanding, which is called life, are drawn to him, so life is automatically drawn to me, as it is impossible for it to be otherwise. [This is the case] even though he did not intend it for himself

(6) Moreover he [=Hillel] saw a skull floating on the face of the water.

He said to it:

because you drowned others, they drowned you.

And in the end, they that drowned you will be drowned.