אֱמֶ֣ת קְ֭נֵה וְאַל־תִּמְכֹּ֑ר חָכְמָ֖ה וּמוּסָ֣ר וּבִינָֽה׃
진리를 사고서 팔지 말며 지혜와 훈계와 명철도 그리할지니라
Mishneh Torah, Torah Study
Where the custom of the state is to pay a beginner's teacher, he should give him his wages, and the obligation to pay for his son's education continues until he is through reading all of the Holy Writ. In a place where the prevailing custom is to teach the written Torah for pay, one may instruct for pay; but to instruct the Oral Torah for wages, is forbidden, as it is said: "Behold, I have taught you statutes and ordinances, even as the Lord my God commanded me, etc." (Deut. 4.5.), which means; "Even as I was instructed free so have you received instruction from me free; likewise when you will give instruction throughout the generations, instruct free even as you were instructed by me." (Nedarim, 37a; Bekorot, 29a). If he find not one who is so willing to teach him gratuitously, he may hire one for wages to be instructed by him, as it says: "Buy the truth" (Prov. 23.23.) Peradventure, one will deduct herefrom that he may instruct others for wages? The Verse, therefore, teaches us, saying: "But sell it not" (Ibid.) Herefrom you learn that one is forbidden to instruct others for hire although his master taught him for hire.