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, Ge 12:4; and this exactly agrees with the account of Demetrius, as related by Polyhistor, an Heathen writer , 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, Ge 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 , Isaac was born A. M. 2108, and before Christ 1896, and probably at Beersheba, see Ge 21:33.
Apud Euseb. Praepar. Evangel. l. 9. c. 21. p. 425. Annales Vet. Test. p.