Genesis 15:13-16

13And he said to Abram, Know assuredly that thy seed will be a sojourner in a land [that is] not theirs, and they shall serve them; and they shall afflict them four hundred years.

14But also that nation which they shall serve I will judge; and afterwards they shall come out with great property.

15And thou shalt go to thy fathers in peace; thou shalt be buried in a good old age.

16And [in the] fourth generation they shall come hither again; for the iniquity of the Amorites is not yet full.