Abram's wife Sarai had not borne him children. She owned an Egyptian slave named Hagar.
References for Genesis 16:1
Sarai said to Abram, "Since the Lord has prevented me from bearing children, go to my slave; perhaps I can have children by her." And Abram agreed to what Sarai said.
References for Genesis 16:2
So Abram's wife Sarai took Hagar, her Egyptian slave, and gave her to her husband Abram as a wife for him. [This happened] after Abram had lived in the land of Canaan 10 years.
He slept with Hagar, and she became pregnant. When she realized that she was pregnant, she looked down on her mistress.
References for Genesis 16:4
Then Sarai said to Abram, "You are responsible for my suffering! I put my slave in your arms, and ever since she saw that she was pregnant, she has looked down on me. May the Lord judge between me and you."
References for Genesis 16:5
Abram replied to Sarai, "Here, your slave is in your hands; do whatever you want with her." Then Sarai mistreated her so much that she ran away from her.
References for Genesis 16:6
The Angel of the Lord found her by a spring of water in the wilderness, the spring on the way to Shur.
He said, "Hagar, slave of Sarai, where have you come from, and where are you going?" She replied, "I'm running away from my mistress Sarai."
Then the Angel of the Lord said to her, "You must go back to your mistress and submit to her mistreatment."
References for Genesis 16:9
The Angel of the Lord also said to her, "I will greatly multiply your offspring, and they will be too many to count."
Then the Angel of the Lord said to her: You have conceived and will have a son. You will name him Ishmael, for the Lord has heard your [cry of] affliction.
References for Genesis 16:11
This man will be [like] a wild ass. His hand will be against everyone, and everyone's hand will be against him; he will live at odds with all his brothers.
So she named the Lord who spoke to her: The God Who Sees, for she said, "Have I really seen here the One who sees me?"
References for Genesis 16:13
That is why she named the spring, "A Well of the Living One Who Sees Me." It is located between Kadesh and Bered.
References for Genesis 16:14
So Hagar gave birth to Abram's son, and Abram gave the name Ishmael to the son Hagar had.
Abram was 86 years old when Hagar bore Ishmael to him.