But the mercy of the LORD is from everlasting to everlasting upon them that fear him, and his righteousness unto children's children;
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Augustine of Hippo
21. In thy reflections therefore on thyself, think of thy low estate, think of thy dust: be not lifted up: if thou art anything better, thou wilt be so by His Grace, thou wilt be so by His mercy. For hear what followeth: "but the mercy of the Lord endureth for ever and ever upon them that fear Him" (ver. 17). Ye who fear not Him, will be grass, and in grass, and in torment with the grass: for the flesh shall arise unto the torment. Let those who fear Him rejoice, because His mercy is upon them.
Justice. In protecting the oppressed, (Calmet) and rendering to every one according to his deserts abundantly. (Haydock)
God never punishes more than a person's crimes have merited, Exodus xx. 5., and xxxiv. 6. (Calmet)