Mishnà su Salmi 55:78

Whoever possesses these three things, he is of the disciples of Abraham, our father; and [whoever possesses] three other things, he is of the disciples of Balaam, the wicked. A good eye, a humble spirit and a moderate appetite he is of the disciples of Abraham, our father. An evil eye, a haughty spirit and a limitless appetite he is of the disciples of Balaam, the wicked. What is the difference between the disciples of Abraham, our father, and the disciples of Balaam, the wicked? The disciples of Abraham, our father, enjoy this world, and inherit the world to come, as it is said: “I will endow those who love me with substance, I will fill their treasuries” (Proverbs 8:21). But the disciples of Balaam, the wicked, inherit gehinnom, and descend into the nethermost pit, as it is said: “For you, O God, will bring them down to the nethermost pit those murderous and treacherous men; they shall not live out half their days; but I trust in You” (Psalms 55:24).

One who learns from his fellow one chapter, or one halakhah, or one verse, or one word, or even one letter, is obligated to treat him with honor; for so we find with David, king of Israel, who learned from Ahitophel no more than two things, yet called him his master, his guide and his beloved friend, as it is said, “But it was you, a man mine equal, my guide and my beloved friend” (Psalms 55:14). Is this not [an instance of the argument] “from the less to the greater” (kal vehomer)? If David, king of Israel who learned from Ahitophel no more than two things, nevertheless called him his master, his guide and his beloved friend; then in the case of one who learns from his fellow one chapter, or one halakhah, or one verse, or one word, or even one letter, all the more so he is under obligation to treat him with honor. And “honor’” means nothing but Torah, as it is said, “It is honor that sages inherit” (Proverbs 3:35). “And the perfect shall inherit good” (Proverbs 28:10), and “good” means nothing but Torah, as it is said, “For I give you good instruction; do not forsake my Torah” (Proverbs 4:2).