Genesis 17:15-18 NIV

15 God also said to Abraham, “As for Sarai your wife, you are no longer to call her Sarai; her name will be Sarah. 16 I will bless her and will surely give you a son by her. I will bless her so that she will be the mother of nations; kings of peoples will come from her.”

17 Abraham fell facedown; he laughed and said to himself, “Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?” 18 And Abraham said to God, “If only Ishmael might live under your blessing!”

Genesis 18:10-15 NIV

10 Then one of them said, “I will surely return to you about this time next year, and Sarah your wife will have a son.”

Now Sarah was listening at the entrance to the tent, which was behind him. 11 Abraham and Sarah were already very old, and Sarah was past the age of childbearing. 12 So Sarah laughed to herself as she thought, “After I am worn out and my lord is old, will I now have this pleasure?”

13 Then the Lord said to Abraham, “Why did Sarah laugh and say, ‘Will I really have a child, now that I am old?’ 14 Is anything too hard for the Lord? I will return to you at the appointed time next year, and Sarah will have a son.”

15 Sarah was afraid, so she lied and said, “I did not laugh.”

But he said, “Yes, you did laugh.”