John Calvin Commentary Genesis 26:1

"And there was a famine in the land, besides the first famine that was in the days of Abraham. And Isaac went unto Abimelech king of the Philistines, unto Gerar." — Genesis 26:1 (ASV)

And there was a famine. Moses relates that Isaac was tried by nearly the same kind of temptation as that through which his father Abraham had twice passed. I have previously explained how severe and violent this assault was.

The condition in which it was God's will to place His servants, as strangers and pilgrims in the land He had promised to give them, seemed sufficiently troublesome and hard. But it appears even more intolerable that He scarcely allowed them to exist (so to speak) in this wandering, uncertain, and changeable kind of life, but almost consumed them with hunger.

Who would not say that God had forgotten Himself, when He did not even supply His own children—whom He had received into His special care and trust—with food, however sparingly and scantily? But God thus tried the holy fathers, so that we might be taught by their example not to be weak and cowardly under temptations.

Regarding the terms here used, we may observe that although there were two periods of famine in Abraham's time, Moses alludes only to the one of which the remembrance was most recent.