After the birth of Isaac, Sarah saw Ishmael son of Hagar engaged in an action described by the verse as metzahek, literally, laughing or playing. Therefore, she requested that Abraham banish him and his mother. What precisely did Sarah see, and what is the meaning of the term metzahek? The Sages provide several explanations.

Rabbi Akiva taught: “Sarah saw the son of Hagar the Egyptian, whom she bore to Abraham, metzahek” (Genesis 21:9). Tzehok stated here means nothing other than idolatry, as it is stated: “And the people sat to eat and drink, and they rose to frolic [letzahek]” (Exodus 32:6). This teaches that our matriarch Sarah saw Ishmael building altars, trapping grasshoppers, and offering and burning the grasshoppers for idol worship. Rabbi Eliezer son of Rabbi Yosei HaGelili says: (Tosefta [Lieberman], Sota 6:6)