Gen 21:15

“(Verse 15, 16.) And she put the boy under a tree, and went and sat opposite him, as if shooting an arrow. She said, 'I will not see the death of my child.' And she sat opposite him. And immediately it happened: The boy cried out, and wept, and God heard the voice of the boy from the place where he was. And the Angel of God called to Hagar from heaven, and so on, let no one move. In Hebrew, after what is written, 'I will not see the death of my child,' it is read that Hagar herself sat opposite the boy, and raised her voice, and wept, and God heard the voice of the child. For when the mother was weeping and waiting miserably for the death of her son, God heard the boy, of whom He had promised to Abraham, saying: 'But I will also make your slave woman's son into a great nation' (Gen. XVII, 20). Otherwise, the mother herself mourned not her own death, but that of her son. Therefore, God spared her, for whom there had been weeping. Finally, it is said in what follows: 'Rise up and take the boy, and hold his hand' (Gen. XVII, 18). From this it is clear that the one who is held is not a burden to his mother, but a companion. And when someone is held by the hand of a parent, their concerned affection is shown.”

“AND SHE CAST THE CHILD. Thirst overtook him and he was unable to walk, and so his mother laid him under the tree, cast away and abandoned. It may be that the word vatashleich (and she cast) is similar in sense to the verses: And He cast them into another land; Cast me not away from Thy presence, meaning “sending away.” Rabbi Abraham ibn Ezra said: “And she cast for she had taken him onto her lap when he was weakened by thirst, [and seeing that he was expiring from thirst, she cast him from her].” Our Rabbis have said that he was sick at the time he sent him away, and therefore he put the child on her shoulder. This is the sense of the word vatashleich (and she cast) him: [until that point she had carried him]. All this occurred to Abraham because he had been commanded to do whatever Sarah said, and she commanded that he send him away immediately, and it was at her command that he did not give them silver and gold, servants, and camels to bear them.”