On the day that Isaac is weaned, Abraham gives a celebratory feast at which “Sarah saw [Ishmael] the son of Hagar the Egyptian, whom she had borne to Abraham, laughing. So, she said to Abraham, ‘Cast out this slave woman with her son!’” (Gen 21:9-10). Sarah’s reaction to Ishmael’s laughter seems totally out of proportion. Since when is “laughing” a crime punishable by expulsion? What was it about Ishmael’s behavior that got Sarah so upset?
Much interpretational ink has been spilled trying to ascertain what Ishmael was doing when Sarah saw him “laughing” (מצחק; metzaheq). The rabbis offer several meanings for מצחק, including sexual immorality, idolatry, and even bloodshed (see Genesis Rabbah 53:11). Even today, Bible translators are trying to make sense of this term; the ESV translates מצחק as “laughing” but, in an attempt to square Ishmael’s punishment with his “crime,” the translators provide a speculative footnote: “Possibly laughing in mockery.” However, there are more appropriate Hebrew words for “mock” than מצחק—e.g., תהל (tahal;1 Kgs 18:27) or תעע (ta’a; cf. Gen 27:12)—so “mockery” may not be the best way to understand Ishmael’s behavior.
When Sarah gives birth to her son, she names him “Isaac” (יצחק; Yitzhaq), saying, “God has made laughter (צחק; tzhoq) for me; everyone who hears will laugh (יצחק; yitzhaq) with me” (21:6). When Ishmael is seen “laughing” (מצחק) at the feast, his action recalls the name “Isaac,” which means “he laughs” (יצחק). These related Hebrew words point to the notion that Ishmael was not merely “laughing”; rather, he was “Issac-ing”! That is, he was behaving as though he were Isaac, the rightful heir of God’s promise. The idea that Ishmael was “trying to be like Isaac” makes more sense of Sarah’s words to Abraham: “Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac” (21:10).