The biblical verse is blunt. Sarah tells Abraham to cast out the handmaid and her son. But in Targum Pseudo-Jonathan on (Genesis 21:10), the Aramaic adds a sentence that changes everything: and he to make war with Izhak.
Sarah is not reacting to a footrace between boys. She is seeing a future. Ishmael, raised in Abraham's household, will one day raise his hand against her son. The Targum of Pseudo-Jonathan, which consistently amplifies prophetic insight in the matriarchs, frames her demand as foresight rather than spite.
This reading has deep roots. The Midrash (Bereshit Rabbah 53:11, compiled in the Land of Israel c. 300–500 CE) reads the Hebrew word metzachek, usually translated mocking, as pointing to bloodshed, idolatry, or sexual transgression. Pseudo-Jonathan chooses the first meaning and makes it explicit: war.
The Maggidim taught that Sarah's hardness here is not cruelty but clarity. A mother who sees what is coming does not wait for the blow. The takeaway: sometimes love looks like separation, because love refuses to let harm incubate inside its own walls.