We saw in the last chapter that God had enabled everyone in Abimelek’s household to conceive again but Sarah was still kept barren. Abraham had laughed at the very thought of Isaac being born to Sarah, Sarah now has joyous laughter that God came through for her despite her disbelief and then there is Ishmael who is mocking his new younger brother. The Hebrew texts quite aptly say that Ishmael was laughing at Isaac. That captures the sentiment of everyone involved in this saga.