And Abraham rose up early in the morning, and took bread, and a skin of water, and gave it unto Hagar, putting it on her shoulder, and the child, and sent her away: and she departed, and wandered in the wilderness of Beersheba.
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Eusebius of Emesa
But was the just Abraham inhumane in that he did not even supply Hagar and the boy with a donkey, with all the cattle he possessed? Some say it was a gesture of kindness, so that she would not have to look after the donkey; others say that he did this believing that God would protect the boy. But why does he throw her out in the first place? Was it not that he wished to have peace with his wife? And indeed he really did not want to send her away at all, for it is written that the thing appeared extremely harsh to Abraham. So he would not have done what he did except for the fact that God said to him, let not this matter trouble you, etc. ...
Bread and water. This seems a very slender allowance to be given by a man of Abraham's riches. But he might intend her to go only into the neighbourhood, where he would take care to provide for her. She lost herself in the wilderness, and thus fell into imminent danger of perishing. (Haydock)
This divorce of Agar, and ejection of Ismael, prefigured the reprobation of the Jews. ...