Sarah, at her old age, births a son, Isaac. Abraham is 100 years old when this happens and Sarah laughed with joy after she had Isaac. She had been worrying that she wouldn't have a child and her distrust in God ruined her peace that she could have felt had she just trusted in God. Learn from Sarah and when you have a troubled heart, focus on God's promises and His
word so you can have your peace of mind as you go through trials.

        Sarah couldn't stand the site of Abrahams other son that he made with Sarah’s servant. It didn't matter that the whole thing was her idea, she didn't want to see it and she didn't want Abraham's first born being the heir to all they had, she wanted it to go to her son, Isaac. So out of anger and jealousy Sarah demanded that Abraham make his first born son and his mother leave.  Abraham was obviously upset over this but God told Abraham not to worry, that they would be fine and a nation would be born to Abrahams first born. So Abraham sent them off into the wilderness, and when things got weary and they ran out of water, God showed Hagar a well to nourish her and her son with, and gave her the reassurance that He was taking care of them.

        Abraham then made a covenant with Abimelech, they agreed to be at peace with one another.  Abimelech knew that Abraham was a man of God and had a close relationship with God and didn't want to be on their bad side. He knew that if he crossed Abraham, God would be displeased with him and Abimelech didn't want that. The fear of God created this covenant.