Deuteronomy 28:63

63.And it shall come to pass, that as the Lord rejoiced over you. The wonderful and inestimable love of God towards His people is here set forth, via, that He had rejoiced in heaping blessings upon them; wherefore their depravity was all the more base and intolerable, in that God, though voluntarily disposed to be bountiful, was obliged by it to lay aside His affection for them. But although it is only by a metaphor that God is said to rejoice in destroying the wicked, yet it is not without good reason that this expression is applied to him; that we may know that He can no more fail to be the defender of His Law, and the Avenger of its contempt, than deny Himself. He complains, indeed, by Isaiah, (Isaiah 10:24) that He is unwillingly forced to punish the Jews; but these two things are quite consistent, that He rejoices in His just judgment, and at the same time is mindful of His clemency and indulgence, so that He would rather pardon, if the wickedness of men would allow Him. But this expression of Moses, that God receives consolation from punishing the wicked, constantly occurs in the Prophets.