Talmud zu Tehillim 55:14

Whoever learns from his fellow a single chapter, a single rule, even a single verse or even a single small letter¹⁸The spelling of a word. Cf. the Gemara below. must treat him with honour; for so we find with David, king of Israel, who learnt from Ahitophel only two things,¹⁹For the two lessons, cf. Aboth, Sonc. ed., p. 81, n. 6. yet he treated him as his teacher and guide, as it is stated, But it was thou, a man mine equal, my companion, and my familiar friend.²⁰Ps. 55, 14. Now is there not an argument from minor to major? If David, king of Israel, who learnt from Ahitophel only two things called him his teacher and guide, how much more so must one who learns from his fellow-man a chapter, a rule, a verse, a word or even one letter treat him with honour! And ‘honour’ means nothing but Torah, as it is stated, The wise shall inherit honour;²¹Prov. 3, 35. [it is also stated,] The whole-hearted shall inherit good,²²ibid. XXVIII, 10. and good is nothing else than Torah, as it is stated For I give you good doctrine; forsake ye not my teaching.²³ibid. IV, 2.