Genesis 21:30

30. that it may be a witness] Abimelech’s question and Abraham’s answer are probably the technical terms of the usual transaction. The transfer of the seven lambs having taken place, it was a “witness” to the fact that Abraham was acknowledged by Abimelech to have digged the well. There is no mention of document or writing in the compact.

The Cambridge Bible for Schools and Colleges (gen. ed. J. J. S. Perowne; Cambridge University Press, 1878–1918) — public domain. Text from a community e-Sword module.

And Abraham planted a grove in Beersheba,.... The Jewish writers (w) are divided about the use of this grove, as Jarchi relates; one says it was for a paradise or orchard, to produce fruits out of it for travellers and for entertainment; another says it was for an inn to entertain strangers in; it rather was for a shade, to shelter from the sun in those sultry and hot countries; and perhaps for a religious use, and to be an oratory, as the following words seem to suggest: in the midst of it very likely Abraham built an altar, and sacrificed to the Lord; hence might come the superstitious use of groves among the Heathens; and, when they came to be abused to idolatrous purposes, they were forbidden by the law of Moses, which before were lawful. And, though the name of Abraham is not in the text, there is no doubt but he is designed, and was the planter of the grove, and which is expressed in the Septuagint version, as it is supplied by us. What sort of trees this grove consisted of cannot with certainty be said, very probably the oak. R. Jonah (x) thinks it may be the tree which in Arabic they call "ethel", and is a tree like that which is called tamarisk in general it signifies any tree, and especially large trees (y):

and called there on the name of the Lord, the everlasting God; who, is from everlasting to everlasting, or "the God of the world" (z), the Creator and upholder of it, and the preserver of all creatures in it; him Abraham invoked in this place, prayed unto him, and gave him thanks for all the mercies he had received from him.

(w) In T. Bab. Sotah, fol. 10. 1. (x) Apud Kimchi, Sepher Shorash. rad. (y) Vid. R. Sol. Urbin. Ohel Moed, fol. 72. 1. (z) "Dei seculi", Pagninus, Hontanus, Calvin; so Ainsworth.

John Gill's Exposition of the Whole Bible (1746–1763) — public domain (CC PDM 1.0). Text via the HelloAO Bible API.

That this care of Abraham’s was not superfluous may appear from Gen 26:15.

Matthew Poole's English Annotations on the Holy Bible (1683–1685) — public domain. Text from a community e-Sword/MySword module.

30. Seven ewe lambs shalt thou take of my hand — These seem to have been an additional present to bind the treaty at the well. The receiving of this gift would bind Abimelech by a most solemn stipulation. The Hebrew word for swear, in Gen_21:23-24, is the verbal form of the word for seven, and in its usual Niphal form (נשׁבע) means literally, to seven one’s self. This, perhaps, arose from the custom of confirming or sealing an oath by seven offerings or seven witnesses.

Daniel D. Whedon (gen. ed.), Commentary on the Old and New Testaments (1874–1909) — public domain. Text from a community e-Sword module.

בעבור (supply the word זאת) — IN ORDER THAT this (where this, a feminine form in a neuter sense, as is usual in Hebrew, refers to the incident just recorded).

תהיה לי לעדה MAY BE UNTO ME AS A WITNESS The word עדה means witness in reference to a previous feminine form (in this case to זאת, this, which word Rashi supplied), just as (31:52) “And the pillar is a witness” (עדה the feminine form to correspond with the feminine noun מצבה, whereas the preceding words are עד הגל הזה “this heap is a witness” where עד is masc to agree with Gal.

כי חפרתי את הבאר THAT I HAVE DIGGED THIS WELL —Abimelech’s herdsmen quarrelled about it, saying, “We have dug it”. They arranged amongst themselves that the well should belong to him who would show himself at the well together with his sheep and at whose approach the waters would rise, and they rose at the approach of Abraham and his sheep (Genesis Rabbah 54:5).

Rashi on the Tanakh — English translations: “The Judaica Press complete Tanach with Rashi, translated by A. J. Rosenberg” (CC BY 4.0); “Pentateuch with Rashi's commentary by M. Rosenbaum and A.M. Silbermann, 1929-1934” (public domain); “The Metsudah Tanach series, Lakewood, N.J” (CC BY 4.0); and “The Book of Joshua, Metsudah Publications, 1997” (CC BY 4.0). Text via Sefaria.

ויאמר...תהיה לי לעדה, “this gift that I am giving you shall serve as proof for me.”

Radak on the Tanakh — English translations: “Sefaria Community Translation” (CC0 1.0 (public-domain dedication)); “Eliyahu Munk, HaChut Hameshulash” (CC BY 4.0); “Rabbi Mike Feuer, Jerusalem Anthology” (CC BY 4.0); and “R. David Kimhi on the first book of Psalms, Translated by R.G. Finch, London, 1919” (public domain). Text via Sefaria.