And work not corruption in the land, after it has been set right…He [Sahl] said:[It means that] you should not spoil obedience with sin. This is because whoever persists in sinning, though it be of the smallest kind of prohibited act, will find all his good deeds alloyed by that transgression. Furthermore, his good deeds will not become pure as long as he maintainsjust one misdeed, until he repents and divests himself of that misdeed, thereby purifying them [his good deeds] from the defilement of sins [he commits], both in secret and openly.His words, Exalted is He: