During that period Tuthmosis III, while on his way to or coming back from one of his military campaigns in Asia, stopped over at Abraham's encampment. "That night Yahweh appeared to him and said, 'I am the God of your father. Do not be afraid, for I am with you and I will bless you(...). In that place (Abraham) built an altar and worshipped God. There he pitched his tent and there his servants dug a well" (Gen.26,23-25). The place is Beersheba, in the high valley of Gerar, along the road that unites Egypt with Palestine. It was here that Tuthmosis met Abraham and sealed a pact with him; this is confirmed by the altar raised there, the usual witness to an agreement. The verse at Genesis 26,23 emphasizes the fact that the meeting, for some unknown reason, took place at night.
What
happened that night? What were the exact terms of the agreement? The answers
to these questions are to be found in Genesis 15: 'I am the Lord, who
brought you out of Ur of the Chaldeans to give you this land, to take
possession of it.' But Abraham said, 'O Sovereign Lord, how can I know that I
shall gain possession of it?' So the Lord said to him, 'Bring me a heifer, a
goat and a ram, each three years old, a dove and a young pigeon.' Abraham brought
these to him, cut them in two and arranged the halves opposite each other; the
birds, however, he did not cut in half. (...) After sunset a very dark night
followed. Then a smoking brazier with a flaming torch appeared and passed
between the pieces. On that day Yahweh made a covenant with Abraham and said,
'To your descendants I give this land, from the river of Egypt to the great
river, the Euphrates. (Gen. 15,7-18).
This is a faithful description of a solemn oath-swearing ceremony in use in the Middle East in Abraham's time. God, invoked as guarantor of the maintenance of the oath sworn, symbolized by fire, would pass through the flesh of anyone who perjured himself, as at that moment the fire passed between the two halves of the slaughtered animals. These verses are found in Genesis 15, but from the context it is not possible to determine the period, and even less to define the locality in which this episode occurred. However, since with this pact Abraham gained possession of a territory, we have to locate it at Beersheba, upon the altar raised there on the occasion of Abraham's meeting with Yahweh.
In fact, immediately after the event, Abimelech, who up till then with various kinds of oppression had treated the Patriarch badly, rushed to see him, accompanied by his friend, Ahuzzath, and Phicol, the commander of his forces, to seal a non-aggression pact: "Now we know that the Lord is with you and we thought: let us make a solemn oath between us. Let us make a treaty with you, that you will do us no harm, just as we did not molest you, but always treated you well and sent you away in peace." The two men now negotiate as equals, like two princes with a common border; in fact, they establish this common frontier in that same Beersheba, since Abraham raises a stele there (Gen. 21,23 and 26,28-32).
The passage in Genesis 15, 7-18 is evidently a description of the ceremony by which Tuthmosis invested Abraham with the possession of a territory, raising him to the same level as Abimelech, that is a prince of the Egyptian empire. So what was the extent of the area granted to Abraham as a feudal territory? The confines cited in Genesis 15, 18 are clearly an exaggeration, inserted by the compiler as a minor addition to the original text. The verse refers to two "rivers" that circumscribe the area Yahweh assigned to Abraham, which can be considered quite reasonable. In a land lacking other reference points the beds of water courses constitute natural boundaries which are much easier to define. But the two rivers cited could not possibly have been the Nile and the Euphrates, as the compiler would lead us to believe. The question to be resolved then is, to which rivers does the verse really refer? We have seen that the border between the territorial possessions of Abraham and Abimelech was situated at Beersheba, which is located exactly at the confluence of two wadis. One, which is secondary, may be associated with the "river of Egypt" cited in Genesis 15,18, since it is situated on the Egyptian side; the other originates close to Hebron and flows into the Mediterranean, passing near to ancient Gerar, Abimelech's city. It is the main wadi in that region and it is not difficult to imagine why its inhabitants call it "the great river", distinguishing it from the minor water courses. The name “Euphrates” would have been added later.
So, Abraham's feudal territory must have been that triangle of land circumscribed by the bed of the torrents that flow into each other near Beersheba, and back toward Hebron (see fig.3). A remarkable confirmation of this is to be found in the last verse of Genesis 13: "So Abraham moved his tents and went to live near the great trees of Mamre at Hebron, where he built an altar to the Lord."
Mamre was obviously the first owner of that territory; together with his brothers Eshcol and Aner, he is defined as "allied" with Abraham, and fought under his orders against the Syrian kings who had kidnapped Lot. From this detail we can deduce that these three were probably the Patriarch's vassals.
That altar, raised at Hebron immediately after the pact of alliance with Abimelech at Beersheba, is clearly the witness of a similar pact between Abraham and his northern neighbor and establishes the border between the two, located exactly where the "great river" begins. The name of this "northern neighbor" is never mentioned, but in all probability refers to the "sons of Het." The Hittites, in fact, turn out to be the owners of the land situated in front of the Mamre woods; it is to them that Abraham goes to buy the plot where the tomb of Macpelah, in which Sarah was buried, is located.