Avot 2:10 — Your friend’s honor should be as dear to you as your own.
Berakhot 17a — Berakhot 17a: Rabbi Yochanan ben Zakkai was always careful to greet first anyone whom he met, even a Gentile in the marketplace.
Mishna Bikkurim 3:7 — Originally all who knew how to recite would recite [the declaration at the time of bringing the first fruit to the Temple] whilst those unable to do so would repeat it; but when they refrained from bringing, it was decided that both those who could and those who could not [recite] should repeat the words.