In Genesis chapters 16-18, Sarai, unable to bear children, gives her maidservant Hagar to Abram to conceive an heir. Hagar becomes pregnant, leading to tensions and her eventual flight. An angel comforts Hagar, instructing her to return and prophesying her son, Ishmael, will father a great nation but will live in conflict with others. Abram, at age 99, receives a divine promise of a son through Sarai, now renamed Sarah. This announcement leads to both amusement and skepticism given their advanced ages. God establishes circumcision as a sign of the covenant. The chapters conclude with a visitation by three mysterious men, reaffirming Sarah's impending pregnancy and foretelling the destruction of Sodom and Gomorrah due to their wickedness.