The concept of sin troubled the disciples and was big on display in the Old Testament.
In John 9 Jesus opened the eyes of a man blind from birth, Since this was done on a Sabbath trouble arose from the Pharisees. In the arguments Jesus again claimed his divinity.
In Genesis 20 Abraham claimed Sarah was his sister. Why? Sarah was his half-sister, so Abraham stretched the truth, also called a lie, or sin. The chapter shows God’s protection even when we do wrong.
In Genesis 21 Isaac is born, and when Ishmael is made fun of it, Sarah got angry and Hagar and Ismael were sent away to die in the desert, but God protected them. The chapter also features the treaty between Abraham and Abimelech at Beersheba.