Genesis 17:21 "But My covenant I will establish with Isaac, whom Sarah will bear to you at this season next year."

Genesis 18:10 He said, "I will surely return to you at this time next year; and behold, Sarah your wife will have a son." And Sarah was listening at the tent door, which was behind him.

Genesis 18:14 "Is anything too difficult for the LORD? At the appointed time I will return to you, at this time next year, and Sarah will have a son."

Acts 7:8 "And He gave him the covenant of circumcision; and so Abraham became the father of Isaac, and circumcised him on the eighth day; and Isaac became the father of Jacob, and Jacob of the twelve patriarchs.

Galatians 4:22 For it is written that Abraham had two sons, one by the bondwoman and one by the free woman.

Hebrews 11:11 By faith even Sarah herself received ability to conceive, even beyond the proper time of life, since she considered Him faithful who had promised. (NASB ©1995)