Exodus 17:5

And the Lord said to Mosheh, Pass over before the people, and take with thee some of the elders of Israel, and the rod with which thou didst smite the river take in thy hand, and go from the face of their murmuring.

AND THE ETERNAL SAID UNTO MOSES: PASS ON BEFORE THE PEOPLE. This is similar in usage to the following expressions: he [Joseph] caused them to pass into cities; and I will make thee to pass with thine enemies into a land which thou knowest not. Thus the meaning thereof here is: “go away from them to another place,” [as will be explained further]. Perhaps this is similar to the expressions: and he [Ahimaaz] overran the Cushite; and he [Jacob] himself passed over before them, meaning that he [Jacob] went in the forefront of them.
The purport of this verse is that the people were in Rephidim, and the rock from which the waters were to come was in Horeb,. this being Mount Sinai, according to the opinion of the former ones, or in my opinion, some city near the mountain, as I will yet explain. (18:1). Moses therefore had to go first before the people, to pass on from Rephidim to Horeb — a distance of one more parsah [a Persian mile] or more — from the camp before them. It was for this reason that G-d said to him, Pass on before the people, and take with thee of the elders of Israel… and go. That is to say, “Go until you will see Me stand before you upon the rock in Horeb.” Now Moses hit the rock, and water came out of it. Scripture however does not relate that the congregation and their cattle drank, as it does in the second incident [at the waters of Meribah], for it is self-understood that they did so. It is clear that the people did not go to Horeb to drink, since they did not arrive in front of Mount Sinai until afterwards in the third month. Instead, they sent their young men and their cattle there to draw water and bring it to them, as is customary in camps.
It appears likely to me that the waters — cold flowing waters — came out from the rock in Horeb and flowed to Rephidim, and there the people drank them. This is Scripture’s intent in saying, He brought streams out of the rock, and caused waters to run down like rivers, and it is further written, He opened the rock, and waters gushed out; they ran, a river in the dry places., 105:41. The verse stating, Behold, He smote the rock, that waters gushed out, and streams overflowed,, 78:20. also applies to the rock in Horeb, in line with the plain meaning of Scripture. The second rock in Kadesh, [instead of gushing forth water], became cleft with a sort of spring welling forth waters, and therefore Scripture states, That is ‘the well’ whereof the Eternal said unto Moses, etc.,, 21:16. and Israel said in the Song, ‘The well,’ which the princes digged,, Verse 18. for it was like a well that was dug. It is for this reason that Scripture says there, and the congregation drank, and their cattle,, 20:11. which means that there they drank from it at that place immediately, but here [in Horeb], overflowing rivers came from it and they drank of it in their homes at their will. Now although according to the tradition of our Rabbis, it was all Miriam’s Well, it is possible that on the first occasion [in Horeb] and during all their forty years’ wandering, the waters came gushing out from the rock like overflowing rivers. The second time, [in Kadesh], as a punishment for that which took place there, it became [only] like a dug well that was full of fresh water [not a gushing spring].

עבור לפני העם, and their complaints will cease when they see that you are making an effort to provide their needs.

ומטך אשר הכית בו את היאור, your staff with which you had smitten the river so that the Egyptians had given up looking for water to drink, will now perform the opposite function and provide you with drinking water.

והלכת. from the camp to the rock.