Genesis 21:2
For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
For Sarah conceived,.... This explains what is meant by the Lord's visiting her, and doing to her according to his word, see
and bare Abraham a son in his old age; which circumstance is remarked, that the favour might appear the greater, and the more wonderful; or, "unto", or "for his old age" {n}, for the comfort of him in his old age, who having lived so many years under the promise of a son, and in the expectation of one, even of the promised seed, from whom the Messiah should spring, now has one, than which nothing could yield him greater consolation:
at the set time of which God had spoken to him, Genesis 17:21; God was not only faithful in fulfilling his promise, but in keeping the exact time of it.
{n} wynqzl "pro senectute ejus", Vatablus; "senectuti ejus", Junius & Tremellius.