'Third and Fourth Generation' in the Bible

You may not go down on your faces before them or give them worship: for I, the Lord your God, am a God who will not give his honour to another; and I will send punishment on the children for the wrongdoing of their fathers, to the third and fourth generation of my haters;

Having mercy on thousands, overlooking evil and wrongdoing and sin; he will not let wrongdoers go free, but will send punishment on children for the sins of their fathers, and on their children's children to the third and fourth generation.