1. Mose 21:31

From this circumstance, the place where it occurred received the name שׁבע בּאר, i.e., seven-well, "because there they sware both of them." It does not follow from this note, that the writer interpreted the name "oath-well," and took שׁבע in the sense of שׁבעה. The idea is rather the following: the place received its name from the seven lambs, by which Abraham secured to himself possession of the well, because the treaty was sworn to on the basis of the agreement confirmed by the seven lambs. There is no mention of sacrifice, however, in connection with the treaty (see Gen 26:33). נשׁבּע to swear, lit., to seven one's self, not because in the oath the divine number 3 is combined with the world-number 4, but because, from the sacredness of the number 7, the real origin and ground of which are to be sought in the number 7 of the work of creation, seven things were generally chosen to give validity to an oath, as was the case, according to Herodotus (3, 8), with the Arabians among others. Beersheba was in the Wady es-Seba, the broad channel of a winter-torrent, 12 hours' journey to the south of Hebron on the road to Egypt and the Dead Sea, where there are still stones to be found, the relics of an ancient town, and two deep wells with excellent water, called Bir es Seba, i.e., seven-well (not lion-well, as the Bedouins erroneously interpret it): cf. Robinson's Pal. i. pp. 300ff.

In this chapter we have, I. Isaac, the child of promise born into Abraham's family (Gen 21:1-8). II. Ishmael, the son of the bondwoman, cast out of it (Gen 21:9-21). III. Abraham's league with his neighbour Abimelech (Gen 21:22-32). IV. His devotion to his God (Gen 21:33).