Mishnah 2 - Chapter 1 - Pirkei Avot

Shimon Hatzaddik was the last of the men of the great assembly [and the tradition (hakabalah) remained in his hand. He was high-priest after Ezra.] He was wont to say [(And thus all "R. Ploni says" and "He was wont to say" in this tractate are understood as "This is what he would say always.")]: The world stands on three things [i.e., the world was created for these three things alone]: on Torah [(Shabbath 88a) If Israel had not accepted the Torah, heaven and earth would not have been created, as it is written (Jeremiah 33:25): "If not for My covenant (of Torah), day and night, the statutes of heaven and earth I would not have made"], on avodah [the sacrificial service. For thus did we learn in tractate Ta'anith (27b): If not for the ma'amadoth (the "watches" at the sacrificial services), heaven and earth could not endure. And we find that because of the sacrifices offered up by Noach, He swore that He would never again bring a flood over the world — whence we see that the world endures because of the sacrifices], and on lovingkindness, [as it is written (Psalms 89:3): "The world is built on lovingkindness." Lovingkindness consists of: rejoicing the groom, consoling mourners, visiting the sick, attending upon the dead, and the like.]