Hashem said to Avraham "lech lecha mei'artzecha mimoladetecha, mibeis avicha," leave your birthplace. And Avraham leaves the place of his birth, he goes to Eretz Cana'an. No sooner does he get there then there's a famine, specifically in the land. It was a test, a test to see if Avraham will question Hashem or not. Avraham immediately goes down to Mitzrayim (Egypt), doesn't question Hashem, doesn't have any even shadows of a doubt. He goes with true, perfect bitachon (trust). For eternity, one of the great accomplishments of Avraham Avinu (our forefather Abraham) is the fact that he didn't question G-d.