And Abraham said unto God, O that Ishmael might live before thee!(Genesis 17:18)

And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.(Genesis 17:19)

And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation.(Genesis 17:20)

But my covenant will I establish with Isaac, which Sarah shall bear unto thee at this set time in the next year.

And he left off talking with him, and God went up from Abraham.(Genesis 17:22)

And Abraham took Ishmael his son, and all that were born in his house, and all that were bought with his money, every male among the men of Abraham's house; and circumcised the flesh of their foreskin in the selfsame day, as God had said unto him.(Genesis 17:23)

And Abraham was ninety years old and nine, when he was circumcised in the flesh of his foreskin.(Genesis 17:24)

Other publications related to "Genesis 17:21":

Genesis 22 (part 2)
A sermon on the lessons of Abraham's sacrifice of Isaac, emphasizing the importance of sacrificial giving and obedience, and trusting in God's provision and blessing.

God always keeps what he promises
Dr. Roberto Miranda discusses how Abrahams faith in Gods promises led to his blessings and how trusting in God can lead to fulfillment of promises.

Genesis 17:21 - Cross Reference

And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise. (Galatians 3:29)

By faith he sojourned in the land of promise, as in a strange country, dwelling in tabernacles with Isaac and Jacob, the heirs with him of the same promise: (Hebrews 11:9)

For this is the word of promise, At this time will I come, and Sarah shall have a son. (Romans 9:9)

To perform the mercy promised to our fathers, and to remember his holy covenant; (Luke 1:72)

And he blessed Joseph, and said, God, before whom my fathers Abraham and Isaac did walk, the God which fed me all my life long unto this day, (Genesis 48:15)

Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen. (Romans 9:5)

And Israel took his journey with all that he had, and came to Beersheba, and offered sacrifices unto the God of his father Isaac. (Genesis 46:1)

And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard it in the tent door, which was behind him. (Genesis 18:10)

And the LORD appeared unto him, and said, Go not down into Egypt; dwell in the land which I shall tell thee of: (Genesis 26:2)

For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him. (Genesis 21:2)

Moreover he said, I am the God of thy father, the God of Abraham, the God of Isaac, and the God of Jacob. And Moses hid his face; for he was afraid to look upon God. (Exodus 3:6)

And God heard their groaning, and God remembered his covenant with Abraham, with Isaac, and with Jacob. (Exodus 2:24)

O that thou wouldest hide me in the grave, that thou wouldest keep me secret, until thy wrath be past, that thou wouldest appoint me a set time, and remember me! (Job 14:13)

And he said unto them, It is not for you to know the times or the seasons, which the Father hath put in his own power. (Acts 1:7)

Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this bondwoman shall not be heir with my son, even with Isaac. (Genesis 21:10)

As he spake to our fathers, to Abraham, and to his seed for ever. (Luke 1:55)