Numbers 21:18

The well dug [by princes]. This is the well dug by the princes, Moshe and Aharon.

With their staffs. With the rod.

From the wilderness. It was given to them.

the well which the fathers of the world, Abraham Izhak, and Jakob digged: the princes who were of old digged it, the chiefs of the people: Mosheh and Aharon, the scribes of Israel, found it with their rods; and from the desert it was given to them for a gift.

UMIMIDBAR MATANAH.’ The meaning of this is as Onkelos rendered it [“and from the wilderness it was given to them”], this being an elliptical expression that is common in songs. Thus it is saying that “from the wilderness, which is a land of drought and thirst, was this gift [the well] given to us; and from this gift [of the well which descended] unto the brooks, and from these brooks [ascended] to the heights until Pisgah, which looks down upon the land which is a complete howling wilderness — there was no other brook, nor any other spring of water except for this one.” This was the Well of Miriam in the opinion of our Rabbis, or a well which came out by word of Moses at the command of the Almighty, which Israel had not asked for. For when G-d told Moses, Gather the people together, and I will give them water, streams overflowed from it [the well], and continued unto distant places.

שרים, a reference to Moses and Aaron.

וממדבר מתנה, according to the plain meaning of the text, these are all names of places the Israelites encountered in the course of their journeys and their encampments.

באר חפרוה שרים, this well was not full to its brim such as wells which are filled by waters emptying into it from above.

וממדבר מתנה, this phenomenon demonstrated that its waters originated in the miraculous waters flowing from the rock at Massah and Merivah.

באר חפרהו שרים, “a well dug by princes.” This well was not like other wells in the Bible which had been dug by servants of slaves, as we know from Genesis 26,25, but it was especially honoured through having been dug by Moses, Aaron, as well as the elders of Israel.

במחוקק במשענותם, “with their scepters and their staffs.” In other words, this well was not dug with ordinary tools like ordinary wells, but by employing a rod given Moses by G–d, something that had served as an instrument of producing miracles repeatedly in the past. This serves as proof, that G–d had never objected to Moses hitting the rock in chapter 20 at the waters of strife. Had He objected to that how could the people have rejoiced jubilantly over something that G–d had shown them that He objected to? According to some commentators the “lawgiver,” referred to here is not Hashem but Moses just as it is in Deuteronomy 33,21. Compare the Targum there.

וממדבר מתנה, and from a place called Midbar to Matanah. This is a hint that the well just discussed was so powerful that it turned the surrounding desert area into “a gift.”