Genesis 21:5

And Abraham was an hundred years old, when his son Isaac was born unto him.

EXPOSITORY (ENGLISH BIBLE)

Matthew Henry's Concise Commentary

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, ch. 17:17; 18:13. When the Sun of comfort is risen upon the soul, it is good to remember how welcome the dawning of the day was. When Sarah received the promise, she laughed with distrust and doubt. When God gives us the mercies we began to despair of, we ought to remember with sorrow and shame our sinful distrust of his power and promise, when we were in pursuit of them. This mercy filled Sarah with joy and wonder. God's favours to his covenant people are such as surpass their own and others' thoughts and expectations: who could imagine that he should do so much for those that deserve so little, nay, for those that deserve so ill? Who would have said that God should send his Son to die for us, his Spirit to make us holy, his angels to attend us? Who would have said that such great sins should be pardoned, such mean services accepted, and such worthless worms taken into covenant? A short account of Isaac's infancy is given. God's blessing upon the nursing of children, and the preservation of them through the perils of the infant age, are to be acknowledged as signal instances of the care and tenderness of the Divine providence. See Ps 22:9,10; Ho 11:1,2.

Barnes' Notes on the Bible

Isaac is born according to promise, and grows to be weaned. "The Lord had visited Sarah." It is possible that this event may have occurred before the patriarchal pair arrived in Gerar. To visit, is to draw near to a person for the purpose of either chastising or conferring a favor. The Lord had been faithful to his gracious promise to Sarah. "He did as he had spoken." The object of the visit was accomplished. In due time she bears a son, whom Abraham, in accordance with the divine command, calls Isaac, and circumcises on the eighth day. Abraham was now a hundred years old, and therefore Isaac was born thirty years after the call. Sarah expressed her grateful wonder in two somewhat poetic strains. The first, consisting of two sentences, turns on the word laugh. This is no longer the laugh of delight mingled with doubt, but that of wonder and joy at the power of the Lord overcoming the impotence of the aged mother. The second strain of three sentences turns upon the object of this admiring joy. The event that nobody ever expected to hear announced to Abraham, has nevertheless taken place; "for I have borne him a son in his old age." The time of weaning, the second step of the child to individual existence, at length arrives, and the household of Abraham make merry, as was wont, on the festive occasion. The infant was usually weaned in the second or third year 1 Samuel 1:22-24; 2 Chronicles 31:16. The child seems to have remained for the first five years under the special care of the mother Leviticus 27:6. The son then came under the management of the father.

Jamieson-Fausset-Brown Bible Commentary

3, 4. Abraham called the name of his son … Isaac … and circumcised—God was acknowledged in the name which, by divine command, was given for a memorial (compare Ge 17:19), and also in the dedication of the child by administering the seal of the covenant (compare Ge 17:10-12).

Matthew Poole's Commentary

circ. 1807 No text from Poole on this verse.

Gill's Exposition of the Entire Bible

And Abraham was an hundred years old when son Isaac was born unto him. So that this was years after his departure from Haran, and coming into the land of Canaan, for then he was seventy five years of age, Genesis 12:4; and this exactly agrees with the account of Demetrius, as related by Polyhistor, an Heathen writer (o), who makes Isaac to be born just twenty five years from Abraham's coming into the land of Canaan, and who must be now an hundred years old, being ninety nine at the time the Lord appeared unto him, and promised him a son at the set time the next year, Genesis 17:1. This is observed, both to show the wonderful favour to Abraham, and the faithfulness of God in the exact performance of his promise: according to Bishop Usher (p), Isaac was born A. M. 2108, and before Christ 1896, and probably at Beersheba, see Genesis 21:33.

(o) Apud Euseb. Praepar. Evangel. l. 9. c. 21. p. 425. (p) Annales Vet. Test. p. 9.

Geneva Study Bible

And Abraham was an hundred years old, when his son Isaac was born unto him.

EXEGETICAL (ORIGINAL LANGUAGES)

Pulpit Commentary

Verse 5. - And Abraham was an hundred years old (cf. Genesis 17:1, 17), when his son Isaac was born unto him. Literally, at the time of bearing to him (ἐν τῷ τεκεῖν) Isaac (vide Gesenius, 'Gram.,' § 143). Thus Abraham had waited twenty-five years for the fulfillment of the promise - a remarkable instance of faith and patience (Romans 4:20), as Isaac's birth was a signal display of Divine power (Romans 4:17; Hebrews 11:12). Whether Isaac was born at Gerar or at Beersheba cannot with certitude be inferred. Genesis 21:5

Keil and Delitzsch Biblical Commentary on the Old Testament

Birth of Isaac. - Jehovah did for Sarah what God had promised in Genesis 17:6 (cf. Genesis 18:14): she conceived, and at the time appointed bore a son to Abraham, when he was 100 years old. Abraham gave it the name of Jizchak (or Isaac), and circumcised it on the eighth day. The name for the promised son had been selected by God, in connection with Abraham's laughing (Genesis 17:17 and Genesis 17:19), to indicate the nature of his birth and existence. For as his laughing sprang from the contrast between the idea and the reality; so through a miracle of grace the birth of Isaac gave effect to this contrast between the promise of God and the pledge of its fulfilment on the one hand, and the incapacity of Abraham for begetting children, and of Sarah for bearing them, on the other; and through this name, Isaac was designated as the fruit of omnipotent grace working against and above the forces of nature. Sarah also, who had previously laughed with unbelief at the divine promise (Genesis 18:12), found a reason in the now accomplished birth of the promised son for laughing with joyous amazement; so that she exclaimed, with evident allusion to his name, "A laughing hath God prepared for me; every one who hears it will laugh to me" (i.e., will rejoice with me, in amazement at the blessing of God which has come upon me even in my old age), and gave a fitting expression to the joy of her heart, in this inspired tristich (Genesis 21:7): "Who would have said unto Abraham: Sarah is giving suck; for I have born a son to his old age." מלּל is the poetic word for דּבּר, and מי before the perfect has the sense of - whoever has said, which we should express as a subjunctive; cf. 2 Kings 20:9; Psalm 11:3, etc.