1 Isaac promised in one year

Genesis 18:10-15 (ESV)

10  The LORD said, “I will surely return to you about this time next year, and Sarah your wife shall have a son.” And Sarah was listening at the tent door behind him.

11  Now Abraham and Sarah were old, advanced in years. The way of women had ceased to be with Sarah.

12  So Sarah laughed to herself, saying, “After I am worn out, and my lord is old, shall I have pleasure?”

13  The LORD said to Abraham, “Why did Sarah laugh and say, ‘Shall I indeed bear a child, now that I am old?’

14  Is anything too hard for the LORD? At the appointed time I will return to you, about this time next year, and Sarah shall have a son.”

15  But Sarah denied it, saying, “I did not laugh,” for she was afraid. He said, “No, but you did laugh.”