Charles Ellicott Commentary Genesis 15:13

"And he said unto Abram, Know of a surety that thy seed shall be sojourners in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years;" — Genesis 15:13 (ASV)

Four hundred years. —The exact duration of the sojourn in Egypt was 430 years (Exodus 12:40–41), and with this agrees the genealogy of Jehoshua (1 Chronicles 7:23–27).