מדרש אויף משלי 27:7

Raba said again unto Rabba bar Mari: "Wherefrom the following saying: 'If thou wilt lift the burden, I shall [also] lift (if you will share the responsibility, then I will lead); and if not, I will not touch it?" He answered: "From (Judges 4, 8) If thou wilt go with me, then I will go; but if thou wilt not go with me, I will not go." Raba said again to Rabba bar Mari: "Wherefrom the following saying: 'When thou hast called thy neighbor [cautioning him], and he would not answer, push down a big wall and throw it at him?'" He answered: "From (Ezek. 24, 13) Because I have purged thee, and thou wast not purged, thou shalt not be purged from thy filthiness any more." Raba said again to Rabba bar Mari: "Wherefrom the following saying: 'Do not spit in the well from which you drank water?'" He answered: "From (Deut. 23, 8) Thou shalt not abhor an Edomite; for he is thy brother; thou shalt not abhor an Egyptian; because thou wast a stranger in his land." Rabba said again to Rabba bar Mari: "Wherefrom the following: When we were young, we were esteemed as men, now that we are old we are considered as children?" He replied: "In the beginning it is written (Ex. 13, 21) And the Lord went before them … and by night in a pillar of fire, to give light to them; and thereafter (Ib. 23, 20) Behold, I send an angel before thee, to keep thee by the way."

R. Shimon b. Yochai says: It is written (Proverbs 27:7) "The sated soul will tread down a honeycomb": This is a Torah scholar who did not learn from the beginning; "but to the hungry soul all bitter is sweet": This is one who did learn (from the beginning). Variantly: "The sated soul will tread down a honeycomb (nofeth)": Just as a sieve extracts flour by itself, bran flour by itself, and wheat flour by itself, so, a Torah scholar sits and scrutinizes words of Torah and weighs them — This sage forbids, this sage permits; this sage rules unclean; this sage rules clean.