Shimon HaTzaddik was from the remnants of the Great Assembly. He used to say: On three things the world stands: On Torah, On service [of God], And on acts of human kindness. .
Pirke Avos Chapter 1, Mishna 2 (2017)
Pirke Avos Chapter 1, Mishna 1 (2017)
Moses received Torah from Sinai and handed it down to Joshua; and Joshua to the Elders; and the Elders to the Prophets; and the Prophets handed it down to the members of the Great Assembly. They said three things: Be deliberate in judgement, stand up many students, and make a fence for the Torah.