Genesis 17:1-7, 15-16

When Abram was ninety-nine years old, the LORD appeared to Abram and said to him, “I am Almighty God; walk before Me and be blameless. And I will make My covenant between Me and you, and will multiply you exceedingly.” Then Abram fell on his face, and God talked with him, saying: “As for Me, behold, My covenant is with you, and you shall be a father of many nations. No longer shall your name be called Abram, but your name shall be Abraham; for I have made you a father of many nations. I will make you exceedingly fruitful; and I will make nations of you, and kings shall come from you. And I will establish My covenant between Me and you and your descendants after you in their generations, for an everlasting covenant, to be God to you and your descendants after you.

Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. And I will bless her and also give you a son by her; then I will bless her, and she shall be a mother of nations; kings of peoples shall be from her.”