And as, in those times, vengeance came from God upon the Egyptians who were subjecting Israel to unjust punishment, so is it now, the Lord truly declaring, "And shall not God avenge His own elect, which cry day and night unto Him? I tell you, that He will avenge them speedily." So says the apostle, in like manner, in the Epistle to the Thessalonians: "Seeing it is a righteous thing with God to recompense tribulation to them that trouble you; and to you who are troubled rest with us, at the revealing of our Lord Jesus Christ from heaven with His mighty angels, and in a flame of fire, to take vengeance upon those who know not God, and upon those that obey not the Gospel of our Lord Jesus Christ: who shall also be punished with everlasting destruction from the presence of the Lord, and from the glory of His power; when He shall come to be glorified in His saints, and to be admired in all them who have believed in Him."
Source: Against Heresies Book 4