תּלמוד אויף קהלת 5:9

Rabbi Simai expounded: "What is that which is written, 'One who loves money will not be satisfied with money, nor one who loves wealth with income' (Ecclesiastes 5:9)? 'One who loves money will not be satisfied with money'—that's Moses our teacher, who knew that the three cities across the Jordan would not be effective at providing refuge until the three in the land of Canaan were chosen, but he said: 'A mitzvah has come to my hand and I will fulfil it!' [Understanding 'money' here to be 'mitzvot].

(Pneumonic: Ashi lilmod, Ravina lelameid). Rav Ashi said:

Ravina said: "Anyone who loves to teach in public, that is his reward." And this [is similar to] what Rabbi said: "I have learnt a lot of Torah from my teachers, and my colleagues are greater than them—and my students are greater than all of them!"