He who learns from his fellowman a single chapter, a single halakha, a single verse, a single Torah statement, or even a single letter, must treat him with honor. For so we find with David King of Israel, who learned nothing from Ahitophel except two things, yet called him his teacher (in Hebrew: rabbo meaning ‘his rabbi’), his guide, his intimate, as it is said: 'You are a man of my measure, my guide, my intimate' (Psalms 55:14). One can derive from this the following: If David King of Israel who learned nothing from Ahitophel except for two things, called him his teacher (i.e. rabbo -- his "rabbi"), his guide, his intimate, one who learns from his fellowman a single chapter, a single halakha, a single verse, a single statement, or even a single letter, how much more must he treat him with honor. And honor is due only for Torah, as it is said: 'The wise shall inherit honor' (Proverbs 3:35), 'and the perfect shall inherit good' (Proverbs 28:10). And only Torah is truly good, as it is said: 'I have given you a good teaching, do not forsake My Torah' (Psalms 128:2). (Ethics of the Fathers 6:3)