Eusebius of Caesarea

He does not say that fire came down from heaven upon the wicked Sodomites before that Lot went out from them, just as the deluge did not swallow up the inhabitants of the earth before that Noah entered the ark; for as long as Noah and Lot dwelt with the wicked, God suspended His anger that they might not perish together with the sinners, but when He would destroy those, He withdrew the righteous. So also at the end of the world, the consummation shall not come before all the just are separated from the wicked.