17:1 When Abram was ninety-nine years old the Lord appeared to Abram and said to him, “I am God Almighty;  walk before me, and be blameless, 2 that I may make my covenant between me and you, and may multiply you greatly.” 3 Then Abram fell on his face. And God said to him, 4 “Behold, my covenant is with you, and you shall be the father of a multitude of nations. 5 No longer shall your name be called Abram,  but your name shall be Abraham,  for I have made you the father of a multitude of nations. 6 I will make you exceedingly fruitful, and I will make you into nations, and kings shall come from you. 7 And I will establish my covenant between me and you and your offspring after you throughout their generations for an everlasting covenant, to be God to you and to your offspring after you.
15 And God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah  shall be her name. 16 I will bless her, and moreover, I will give  you a son by her. I will bless her, and she shall become nations; kings of peoples shall come from her.” (ESV)