Gen 20-22 covers Abraham's treachery (20), the birth of Isaac (21a), Sarah turning against Hagar (21b), the covenant with Abimelech (21c), and the offering of Isaac (22).
Here are some interesting notes on this section:
Amazingly in Ch. 20, Abraham tries the same old "she is not my wife, she is my sister" routine. Once again a heathen king has to rebuke him once he discovers the truth. Also in 20, we see the word prophet used for the first time.
In Ch. 21, the reason Sarah gets so angry at Hagar is because her son mocks a young Isaac.
In Ch. 22 we come to the familiar story of Isaac and the sacrifice. God never intended for Abraham to kill Isaac, rather He wanted to see if Abraham would be willing to give up his first and only son to God. Many many years later, God would indeed give up His Son (Jesus Christ) for the salvation of all mankind.
