There was a famine] probably occasioned by the depredations of the Philistines, Ammonites, carrying off the corn as soon as it was ripe, or destroying it on the field.
The Targum says: “God has decreed ten grievous famines to take place in the world, to punish the inhabitants of the earth, before the coming of Messiah the king. The first in the days of Adam; the second in the days of Lamech; the third in the days of Abraham; the fourth in the days of Isaac; the fifth in the days of Jacob; the sixth in the days of Boaz, who is called Abstan, (Ibzan,) the just, of Beth-lehem-judah; the seventh in the days of David, king of Israel; the eighth in the days of Elijah the prophet; the ninth in the days of Elisha, in Samaria; the tenth is yet to come, and it is not a famine of bread or of water but of hearing the word of prophecy from the mouth of the Lord; and even now this famine is grievous in the land of Israel.”
That is, Jacob heard from the report of others that there was plenty in Egypt. The operations of one sense, in Hebrew, are often put for those of another. Before agriculture was properly known and practised, famines were frequent; Canaan seems to have been peculiarly vexed by them. There was one in this land in the time of Abraham, Ge 12:10; another in the days of Isaac, Ge 26:1; and now a third in the time of Jacob. To this St. Stephen alludes, Ac 7:11: there was great affliction, and our fathers found no sustenance.