Genesis 19-21 covers a range of pivotal events. Chapter 19 details the destruction of Sodom and Gomorrah due to their wickedness. Lot, Abraham's nephew, narrowly escapes this devastation, but his wife turns into a pillar of salt for looking back. Later, in isolation, Lot's daughters conspire to preserve their family line through their father, leading to the birth of the Moabite and Ammonite ancestors. Chapter 20 sees Abraham moving to Gerar, where he again presents Sarah as his sister, prompting King Abimelech to take her. However, God intervenes, revealing the truth to Abimelech in a dream. In Chapter 21, the promised son, Isaac, is born to Abraham and Sarah, bringing joy but also tension. Sarah demands the expulsion of Hagar and her son, Ishmael. God assures Abraham of Ishmael's future before the mother and son are cast out, only to be divinely rescued in the wilderness.