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.
Then the Lord said to Abram, “You can be sure that your descendants will be strangers and travel in a land they don’t own. The people there will make them slaves and be cruel to them for four hundred years.
After your great-great-grandchildren are born, your people will come to this land again. It will take that long, because I am not yet going to punish the Amorites for their evil behavior.”
This is what I mean: God had an agreement with Abraham and promised to keep it. The law, which came four hundred thirty years later, cannot change that agreement and so destroy God’s promise to Abraham.