Why did God let Sarah send Hagar and Ishmael away?
Because the inheritance promised to Abraham would pass through one son, not two — and the Hebrew text says that quietly through a pun and an imperative. Sarah used the same verb that drove Adam from Eden and Cain from the ground, and Yahweh told Abraham to listen to her voice.
It is one of the hardest moments in the Abraham story. The boy who had grown up in the household — Abraham's firstborn son — is sent away with his mother into the wilderness, with bread and a single skin of water. And the verse before tells us God told Abraham to do it.
The trigger was the day Isaac was weaned. Sarah saw Ishmael at the feast and said something blunt:
וַתֹּ֙אמֶר֙ לְאַבְרָהָ֔ם גָּרֵ֛שׁ הָאָמָ֥ה הַזֹּ֖את וְאֶת־בְּנָ֑הּ כִּ֣י לֹ֤א יִירַשׁ֙ בֶּן־הָאָמָ֣ה הַזֹּ֔את עִם־בְּנִ֖י עִם־יִצְחָֽק
va-tomer le-Avraham garesh ha-amah ha-zot ve-et bnah ki lo yirash ben ha-amah ha-zot im bni im Yitzhak
"And she said to Abraham: cast out this slave woman and her son, for the son of this slave woman shall not inherit with my son, with Isaac." — Genesis 21:10
Two Hebrew verbs sit in that sentence and they are nearly the same word. Garash (H1644) means "cast out." Yarash (H3423) means "inherit." Three consonants — ג־ר־שׁ and י־ר־שׁ — the same sounds in a different order. Sarah is making a pun on her grief. One son will be driven out so the other may inherit.
The first verb is heavier than it looks. In all of Genesis, garash appears in only three verses. Yahweh used it when he drove the man out of Eden (Genesis 3:24). Cain used it when he complained that Yahweh had driven him from the face of the ground (Genesis 4:14). And Sarah is the third — the only human in Genesis to actually speak this verb, and she speaks it as a command to her husband. It is the verb of Edenic expulsion, and now it falls on Hagar's household.
Abraham did not want to do it. The next verse says the thing was "exceedingly grievous in Abraham's eyes on account of his son." Then God spoke:
"Do not let it be grievous in your eyes on account of the lad and on account of your slave woman. In all that Sarah says to you, listen to her voice, for in Isaac shall your seed be called." — Genesis 21:12
Yahweh ratifies Sarah's imperative. The Hebrew is shema be-qolah — "listen to her voice" — and the verb shama ("hear, listen") is the verb of Ishmael's own name (Yishma'el, "El hears"). The boy's name will be vindicated nine verses later when God hears the lad himself, in the wilderness. But here the verb tells the father to obey the mother's word.
The reason God gave is the one the New Testament will quote twice. The seed-line, the line that would carry the promise forward to Christ, would be reckoned through Isaac, not through Ishmael. That is not a judgment on Ishmael's worth — verse thirteen immediately promises that God will make Ishmael himself into a nation, because he too is Abraham's seed. Two sons, two futures. But only one inheritance.
Paul reads this scene at Galatians chapter four and applies the same imperative to the two covenants — the one that enslaves and the one that frees. The writer of Hebrews reads the next clause ("in Isaac shall your seed be called") as the ground for Abraham's faith at the Akedah. The expulsion was painful. It was also, the text says, the path the promise had to take.
The full study traces the Edenic expulsion-verb, the garash / yarash pun, and Yahweh's ratification — and how Genesis 21:14 sets the stage for the morning Abraham will rise again, in chapter twenty-two, to walk Isaac up Mount Moriah.
How does Mary's Magnificat connect to Sarah at Genesis 21?
Through one Hebrew verb that the Greek Old Testament translates with a single Greek verb — and Luke's birth narrative reuses it in the exact aorist tense the Septuagint used at Sarah's womb. The connection is not thematic resemblance; it is one word traced across the entire canon.
What does «in Isaac shall your seed be called» mean?
It means the promise God gave Abraham would run forward through one specific son — Isaac — and the descendants reckoned to that line would be the heirs of the covenant, not all of Abraham's biological children. Two New Testament writers quote this exact five-word Greek clause to settle who counts as Abraham's true children.
Why did Abraham plant a tamarisk at Beersheba?
Because he had just sworn a covenant of peace at a well in a foreign land, and the tree marked a place of worship — the first place anyone in Scripture calls on God as «the Everlasting God.» The tamarisk only appears three times in the entire Old Testament, and the other two are at the death of Saul.