211 And Jehovah visited Sarah as he had said, and Jehovah did unto Sarah as he had spoken. 2 And Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. 3 And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac. 4 And Abraham circumcised his son Isaac when he was eight days old, as God had commanded him. 5 And Abraham was a hundred years old, when his son Isaac was born unto him. 6 And Sarah said, God hath made me to laugh. Every one that heareth will laugh with me. 7 And she said, Who would have said unto Abraham, that Sarah should give children suck? For I have borne him a son in his old age.
Matthew Henry's Commentary on Genesis 21:1-7
Commentary on Genesis 21:1-8
(Read Genesis 21:1-8)
Few under the Old Testament were brought into the world with such expectations as Isaac. He was in this a type of Christ, that Seed which the holy God so long promised, and holy men so long expected. He was born according to the promise, at the set time of which God had spoken. God's promised mercies will certainly come at the time which He sets, and that is the best time. Isaac means "laughter," and there was good reason for the name, Psalm 22:9,10; Hosea 11:1,2.