Genesis 21:1-6 YLT

1 And Jehovah hath looked after Sarah as He hath said, and Jehovah doth to Sarah as He hath spoken;
2 and Sarah conceiveth, and beareth a son to Abraham, to his old age, at the appointed time that God hath spoken of with him;
3 and Abraham calleth the name of his son who is born to him, whom Sarah hath born to him -- Isaac;
4 and Abraham circumciseth Isaac his son, [being] a son of eight days, as God hath commanded him.
5 And Abraham [is] a son of a hundred years in Isaac his son being born to him,
6 and Sarah saith, `God hath made laughter for me; every one who is hearing laugheth for me.'