Sarah gives birth to Isaac

• Sarah bore a son to Abraham, at the time of which G-d had spoken to him. Abraham named him Isaac and circumcised him when he was eight days old, as G-d had commanded. Abraham was 100 years old, at that time. When Isaac was weaned, Abraham made a great feast.

Sarah drives out Hagar and Ishmael, but G-d saves them

• Sarah saw Ishmael making merry and asked Abraham to drive Hagar and her son out of the household. Abraham was greatly displeased but G-d said to Abraham, "Be not displeased concerning the lad and concerning your handmaid; whatever Sarah tells you, hearken to her voice, for in Isaac will be called your seed. But also the son of the handmaid I will make into a nation, because he is your seed."
• Abraham sent Hagar and her child away. They wandered in the desert of Beer-Sheba. As their water depleted, Hagar cast the child under one of the bushes and sat away from there because she didn’t want to see his death. G-d heard the lad's voice, and an angel called to Hagar, and said: "What is troubling you, Hagar? Fear not, for G-d has heard the lad's voice in the place where he is. Rise, pick up the lad and grasp your hand upon him, for I shall make him into a great nation." And G-d opened her eyes, and she saw a well of water. Ishmael dwelt in the desert, became an archer and his mother found him a wife from Egypt.

Abimelech makes an agreement with Abraham

• Abimelech said to Abraham, "G-d is with you in all that you do” and asked Abraham to swear that he will never lie to him. Abraham did so. Also, Abraham asked Abimelech to return a well that his servants had seized. Abraham placed seven ewe lambs by themselves and said, "For these seven ewe lambs you shall take from my hand, in order that it be to me for a witness that I dug this well." Therefore, he named that place Beer-Sheba, for there they both swore. And he planted an eishel in Beer-Sheba, and he called there in the name of the Lord, the G-d of the world. And Abraham dwelt in the land of the Philistines for many days.

• Isaac (Yitzchak), means "will laugh"
• and was weaned At the end of twenty-four months. — [from Gen. Rabbah 53:10, Keth. 60a]
• a great feast for all the prominent people of the generation were there: Shem, Eber, and Abimelech. — [from Tan. Buber, Vayishlach 23] Cf. Gen. Rabbah 53:10.
• from the land of Egypt from the place where she grew up
• for many days In Hebron he spent twenty-five years, and here twenty-six. (Seder Olam ch. 1).