Midrasz do Koheleta 7:17

(I Sam. 15, 5) And he (Saul) quarreled in the valley, etc. R. Mani explained this to mean that he (Saul) had a quarrel concerning the valley; i.e., when the Holy One, praised be He! said unto Saul (Ib. ib., 3) Go and smite Amaiek, Saul [began to argue and] said: "If for the sake of one soul [that is murdered] the Torah ordered a heifer to be brought in to a wild valley where its neck should be broken [as atonement for the murder], how much more shall I have to suffer for so many souls [should I murder them]? And again, if man sinned, why are the beasts to blame [that I should destroy them also]? And again, if adults sinned, why are the little ones to blame [that I should destroy them also]?" Immediately thereupon, a Bath-Kol went forth and said unto him (Ecc. 7, 16) Be not righteous over much. Later, when Saul gave Doeg the order (I Sam. 22, 18), Turn thou round, and fall upon the priest and kill both men and women; another BathKol went forth and said unto him (Ecc. 7, 17) "Be not wicked over much."

R. Ulla expounded: "What means the passage (Ecc. 7, 17.) Be not wicked too much? A man should not be too wicked, but he may be a little wicked? [It means rather that] if one has eaten garlic causing him to have a bad odor, shall he eat again and let more bad odor come?" Raba b. R. Ulla expounded: "What is meant by the passage (Ps. 73, 4.) For there are no deadly fetters for them; but their strength is firm? i.e., the Holy One. praised be He! said 'It is not sufficient that the wicked do not fear [for future punishment] nor feel any pangs concerning the day of death, but that their heart within them is becoming as strong as the vestibule hall'; and that also is meant by Rabba, for Rabba said: What means the passage (Ib. 49, 14.) This is their way, their folly, i.e., the wicked know that their (wicked) path leads them to death, and their kidneys are becoming fat [without worrying over it]. Perhaps you will say that this is the cause of their forgetting it; therefore it says (Ib.) And they keep the future with pleasure in their mouth, Selah.'"