In Genesis chapter 18 God promised Abraham that his wife Sarah would have a son. The angel of the Lord said to Abraham:
“I will surely return to you about this time next year, and Sarah your wife will have a son.” (Genesis 18.10).
According to the promise, Sarah gave birth to a son, Isaac (Ishaq), who grew to be the heir of Abraham. Sarah and Hagar became jealous of each other because of their sons. Hagar was sent out from the house of Abraham. She went into the desert again and almost died. However, the angel of the Lord saved her by showing her a well of water and told her:
“Lift the boy up and take him by the hand, for I will make him into a great nation.” Genesis 21.18
Ishmael grew and married a woman from Egypt. Isaac grew to manhood in Abraham’s house.