Ps 89:11

“"For who knows the power of Your wrath: and for the fear of You to number Your anger?" [Psalm 90:11]. It belongs to very few men, he says, to know the power of Your wrath; for when Thou dost spare, Your anger is so far heavier against most men; that we may know that labour and sorrow belong not to wrath, but rather to Your mercy, when You chasten and teachest those whom You love, to save them from the torments of eternal punishment: as it is said in another Psalm, "The sinner has provoked the Lord: He will not require it of him according to the greatness of His wrath." With this also is understood, "Who knows?" Such is the difficulty of finding any one who knows how to number Your anger by Your fear, that he adds this, meaning that it is to the purpose that Thou appearest to spare some, with whom You are more angry, that the sinner may be prospered in his path, and receive a heavier doom at the last. For when the power of human wrath has killed the body, it has nothing more to do: but God has power both to punish here, and after the death of the body to send into Hell, and by the few who are thus taught, the vain and seductive prosperity of the wicked is judged to be greater wrath of God.. ..”