Adam Clarke on Genesis 12:10

There was a famine in the land - Of Canaan. This is the first famine on record, and it prevailed in the most fertile land then under the sun; and why? God made it desolate for the wickedness of those who dwelt in it.

Went down into Egypt - He felt himself a stranger and a pilgrim, and by his unsettled state was kept in mind of the city that hath foundations that are permanent and stable, whose builder is the living God. See Heb 11:8, Heb 11:9.