Thirteen years after Ishmael's birth, God appears again to Abram (now 99) and reaffirms the covenant with new details: Abram becomes Abraham; his descendants will be numerous; the land of Canaan is promised; circumcision is the covenant sign for all males. Sarai becomes Sarah; God specifically promises her a son by next year. Abraham laughs in disbelief but God confirms the son will be called Isaac. Ishmael is blessed but the covenant passes through Isaac. Abraham and all the men of his household are circumcised that same day.
God renewed His promise to Abram and gave him a new name — Abraham, father of many nations. The covenant sign was circumcision, and God promised that Sarah would have a son. God's promises always come true, even when they seem impossible.
This chapter introduces two new names: Abram → Abraham ('father of a multitude') and Sarai → Sarah (both mean 'princess'). The new name signals a new identity — God changes who a person is, not just what they do. Circumcision as covenant sign is the outward mark of belonging to God's people. Abraham's laughter (v17) is not mocking but astonished joy — Paul notes in Romans 4:19-21 that Abraham 'did not waver in unbelief.' For children, the key themes are: God keeps His word (even 99 years later!); God gives new names/new identity; Sarah was surprised but God's promises always come true.
God keeps every promise He makes — even when we have to wait a long, long time. We can trust Him because He is Almighty God.