Sforno on Exodus 17:5/ספורנו על שמות י״ז:ה׳

1עבור לפני העם, and their complaints will cease when they see that you are making an effort to provide their needs.

2ומטך 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.

3והלכת. from the camp to the rock.