וַיִּכְל֥וּ הַמַּ֖יִם מִן־הַחֵ֑מֶת וַתַּשְׁלֵ֣ךְ אֶת־הַיֶּ֔לֶד תַּ֖חַת אַחַ֥ד הַשִּׂיחִֽם׃
And the water in the bottle was spent, and she cast the child under one of the shrubs.
Read midrashic interpretation of Genesis 21:15: and classical rabbinic exegesis.