Acts 7:6-8

This is what God said to him: ‘Your descendants will be strangers in a land they don’t own. The people there will make them slaves and will mistreat them for four hundred years. But I will punish the nation where they are slaves. Then your descendants will leave that land and will worship me in this place.’ God made an agreement with Abraham, the sign of which was circumcision. And so when Abraham had his son Isaac, Abraham circumcised him when he was eight days old. Isaac also circumcised his son Jacob, and Jacob did the same for his sons, the twelve ancestors of our people.