Abraham was given a promise that through him all the nations of the earth would be blessed. He had Ishmael born of Hagar, Isaac born of Sarah (son of promise). God said he would also bless Ishmael so Islam has some relationship to God and I believe this is a foreshadowing of the Gentiles coming to faith in Jesus Christ as their Messiah.
“So the child grew and was weaned. And Abraham made a great feast on the same day that Isaac was weaned. And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, scoffing. Therefore she said to Abraham, “Cast out this bondwoman and her son; for the son of this bondwoman shall not be heir with my son, namely with Isaac.” And the matter was very displeasing in Abraham’s sight because of his son. But God said to Abraham, “Do not let it be displeasing in your sight because of the lad or because of your bondwoman. Whatever Sarah has said to you, listen to her voice; for in Isaac your seed shall be called. Yet I will also make a nation of the son of the bondwoman, because he is your seed.” So Abraham rose early in the morning, and took bread and a skin of water; and putting it on her shoulder, he gave it and the boy to Hagar, and sent her away. Then she departed and wandered in the Wilderness of Beersheba. And the water in the skin was used up, and she placed the boy under one of the shrubs. Then she went and sat down across from him at a distance of about a bowshot; for she said to herself, “Let me not see the death of the boy.” So she sat opposite him, and lifted her voice and wept. And God heard the voice of the lad. Then the angel of God called to Hagar out of heaven, and said to her, “What ails you, Hagar? Fear not, for God has heard the voice of the lad where he is. Arise, lift up the lad and hold him with your hand, for I will make him a great nation.” Then God opened her eyes, and she saw a well of water. And she went and filled the skin with water, and gave the lad a drink. So God was with the lad; and he grew and dwelt in the wilderness, and became an archer. He dwelt in the Wilderness of Paran; and his mother took a wife for him from the land of Egypt.”
Genesis 21:8-21 NKJV
“Now the Lord had said to Abram: “Get out of your country, From your family And from your father’s house, To a land that I will show you. I will make you a great nation; I will bless you And make your name great; And you shall be a blessing. I will bless those who bless you, And I will curse him who curses you; And in you all the families of the earth shall be blessed.””
Genesis 12:1-3 NKJV
“For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity. And He came and preached peace to you who were afar off and to those who were near. For through Him we both have access by one Spirit to the Father.”
Ephesians 2:14-18 NKJV