Genesis 15:13-14

13Then the Lord said to Abram, ‘Be sure of this: Your descendants will live in a foreign country. They will be strangers there. People will do bad things to them and they will become slaves. This will continue for 400 years.

14But I will punish the people of that country who give them trouble. After this, your descendants will leave that country. They will take many valuable things with them.