Be angry, and sin not. Let not the sun go down upon your anger.
Lucius Caecilius Firmianus Lactantius
But because I had said that the anger of God is not for a time only, as is the case with man, who becomes inflamed with an immediate excitement, and on account of his frailty is unable easily to govern himself, we ought to understand that because God is eternal, His anger also remains to eternity; but, on the other hand, that because He is endued with the greatest excellence, He controls His anger, and is not ruled by it, but that He regulates it according to His will. And it is plain that this is not opposed to that which has just been said. For if His anger had been altogether immortal, there would be no place after a fault for satisfaction or kind feeling, though He Himself commands men to be reconciled before the setting of the sun. But the divine anger remains for ever against those who ever sin. Therefore God is appeased not by incense or a victim, not by costly offerings, which things are all corruptible, but by a reformation of the morals: and he who ceases to sin renders the anger of God mortal.
Imported from an open dataset — not yet checked against the printed edition.