To fear God is never to pass over any good thing, that ought to be done. Whence it is said by Solomon, Whoso fears God, neglects nothing [Eccl. 7, 18, (Vulg.) 19.]; but because there are some, who practise some good actions, yet in such wise that they are by no means withheld from certain evil practices; after he is said to have been one that feared God, it is still rightly reported of him that he also eschewed evil; for it is written, Depart from evil, and do good [Ps. 37, 27]; for indeed those good actions are not acceptable to God, which are stained in His sight by the admixture of evil deeds; and hence it is said by Solomon, He who offendeth in one point, spoileth many good deeds [Eccl. 9, 18]. Hence James bears witness, saying, For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all. [James 2, 10] Hence Paul saith, A little leaven leaveneth the whole lump [1 Cor. 5, 6]. So then that it might be shewn us how spotless the blessed Job stood forth in his good actions, it is wisely done that we have it pointed out how far he was removed from evil deeds.
[St. Gregory the Great, Moralia in Job, Book I.]