*Minor differences ignored. Grouped by changes, with first version listed as example.
He called it Shebah - This was probably the same well which was called Beersheba in the time of Abraham, which the Philistines had filled up, and which the servants of Isaac had reopened. The same name is therefore given to it which it had before, with the addition of the emphatic letter ה he, by which its signification became extended, so that now it signified not merely an oath or full, but satisfaction and abundance.
The name of the city is Beer-sheba - This name was given to it a hundred years before this time; but as the well from which it had this name originally was closed up by the Philistines, probably the name of the place was abolished with the well; when therefore Isaac reopened the well, he restored the ancient name of the place.
And he called it Sheba,.... Which, according to Jerom, signifies "fulness", as if it had its name from the abundance of water in it; but rather it signifies an "oath", and was so called from the oath, which he and Abimelech had just took to one another; and these circumstances meeting together, the taking of the oath, and the account of the well:
therefore the name of the city is Beersheba unto this day; that is, the well of the oath: it had been so called by Abraham an hundred years ago or more; but now upon this occasion it was renewed and confirmed, and so continued until the times of Moses, and many ages after.
*More commentary available at chapter level.