John Gills Exposition of the Bible Commentary

Verse 21 (Genesis 25:21)

And Isaac entreated the Lord for his wife ,.... Was very earnest and constant in his supplications for her, as the word signifies, as is observed by Jarchi; or, "before his wife" F1 לנכח אשתו "praesente uxore sua", Munster, Fagins. , she being present, and joining with him in his prayers: the reason was:

because she was barren ; which appeared by the length of time they had been married, which was near twenty years, see Genesis 25:26 . The Jewish writers F2 Pirke Eliezer, c. 32. Targum. Jon. in loc. Shalshalet Hakabala, fol. 3. 1. say, that, after twenty years, Isaac took her and went with her to Mount Moriah, to the place where he was bound, and prayed that she might conceive; putting the Lord in mind of the promise he there made of the multiplication of Abraham's seed, Genesis 22:17 ,

and the Lord was entreated of him ; he granted him his request; for, though God has purposed and promised to do many things for his people, yet he will be sought unto by them to do them for them:

and Rebekah his wife conceived ; two sons at once, as it follows.

- John Gills Exposition of the Bible Commentary