Genesis 18:10
10 The Lord said, e“I will surely return to you about this time next year, and fSarah your wife shall have a son.” gAnd Sarah was listening at the tent door behind him.
Genesis 21:1–2
The Birth of Isaac
1 The Lord svisited Sarah as he had said, and the Lord did to Sarah tas he had promised. 2 uAnd vSarah conceived and bore Abraham a son in his old age wat the time of which God had spoken to him.