Babylonian Talmud, Brachot 17a - C

A favorite saying of Raba was: The goal of wisdom is repentance and good deeds, so that a person should not study Torah and Mishna and then despise their father and mother and teacher and superior in wisdom and rank, as it says, “The fear of the Lord is the beginning of wisdom, a good understanding have all they that do thereafter.” It does not say, “that do,” but “that do thereafter,” which implies, that do them for their own sake, and not for other motives. If one does them for other motives, it were better that they had not been created. [CAJE translation. Edited for gender neutrality.]