How many sons did Abraham have?

from the old testament

• Abraham’s first son was Ishmael, born through his wife's maidservant, Hagar (Genesis 16). Abraham was 86 when Ishmael was born (Genesis 16:16).
• Abraham's second son, Isaac, was birthed when Abraham was one hundred years old through his wife, Sarah, who was ninety years old (Genesis 21:2–7). God had told Abraham, "I will make you exceedingly fruitful, and I will make you into nations, and kings shall come from you. 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. And I will give to you and to your offspring after you the land of your sojournings, all the land of Canaan, for an everlasting possession, and I will be their God" (Genesis 17:6–8). God made clear He would establish this covenant with Isaac, the son God would give to Abraham through Sarah (Genesis 17:16, 19).
• Isaac holds a place of importance unlike any of his half-brothers mentioned in the Bible. In fact, God referred to Isaac as "your son, your only son Isaac, whom you love" (Genesis 22:2). Through Isaac came the twelve tribes of Israel, God’s chosen people through whom the Messiah and redemption would come.
• After Sarah's death, Abraham married Keturah, who bore him six sons: Zimran, Jokshan, Medan, Midian, Ishbak, and Shuah (Genesis 25:1–4).
• Because Isaac was the only son born to Abraham's wife, Sarah, Isaac was considered the firstborn son and the sole heir to his father's estate. Genesis 25:5–6 explains, "Abraham gave all he had to Isaac. But to the sons of his concubines Abraham gave gifts, and while he was still living he sent them away from his son Isaac, eastward to the east country." Thus, the other sons became the heads of the tribes who lived east of Israel.
• Genesis 25:12-18 lists Ishmael's twelve sons, who became the leaders of twelve tribes, fulfilling God's promise to make him a great nation. Ishmael lived to be 137 years old, and after his death, his descendants settled in the region from Havilah to Shur, near Egypt, where they lived in hostility toward their relatives. Despite the hostility between Isaac and Ishmael, in Genesis 25:9, after Abraham’s death, both Ishmael and Isaac bury their father, suggesting that despite their earlier separation, they were able to unite in honoring their father. This act indicates a moment of peace between the brothers.

from the new testament

• Abraham’s sons include all those who trust in Christ for salvation. Paul explains, "Know then that it is those of faith who are the sons of Abraham" (Galatians 3:7). Anyone who places their faith in God and the sacrifice of His Son, Jesus, is adopted into Abraham's family and is considered a son of Abraham. Abraham now has innumerable "sons" who have followed his example of faith by trusting God and the promises in His Word (see Romans 4 and Galatians 3:27–28).
• Hebrews 11:11–12 says, "By faith Sarah herself received power to conceive, even when she was past the age, since she considered him faithful who had promised. Therefore from one man, and him as good as dead, were born descendants as many as the stars of heaven and as many as the innumerable grains of sand by the seashore." Isaac is the son through whom God would continue His promise to Abraham to make him a great nation and to bless all the families on the earth (Genesis 12:2–3; 17:15–21). Ultimately this blessing for "all the families on the earth" is speaking of the Messiah who would be born through Isaac's line of descendants—Jesus Christ (see Galatians 3; Matthew 1:1–2; Luke 3:34).

implications for today

Abraham's fatherhood is a good example of how God's Word can be trusted without clambering to fulfill His promises in our own time by our own efforts. Although Abraham and Sarah schemed to birth Ishmael through Hagar in order to secure a descendant, God’s promises came to fruition. In God's timing and by His miraculous hand, Sarah bore Isaac, the son who would fulfill the promise God had made. Now anyone who places their faith in God is considered a son of Abraham (Galatians 3:27–28). Thus, God's promise "I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing" has come true (Genesis 12:2). We often try to take control and do things the way we think is best instead of trusting in what the Lord has said. Waiting for God’s promises to be fulfilled does not mean inactivity, but it means working faithfully the way He has called us to live as we wait for what is yet to come.