הִנְנִ֣י עֹמֵד֩ לְפָנֶ֨יךָ שָּׁ֥ם ׀ עַֽל־הַצּוּר֮ בְּחֹרֵב֒ וְהִכִּ֣יתָ בַצּ֗וּר וְיָצְא֥וּ מִמֶּ֛נּוּ מַ֖יִם וְשָׁתָ֣ה הָעָ֑ם וַיַּ֤עַשׂ כֵּן֙ מֹשֶׁ֔ה לְעֵינֵ֖י זִקְנֵ֥י יִשְׂרָאֵֽל׃
Narito, tatayo Ako sa harap mo roon sa ibabaw ng bato sa Horeb; at hahampasin mo ang bato, at lalabas mula roon ang tubig, at iinom ang bayan.” At gayon nga ang ginawa ni Moises sa paningin ng matatanda ng Israel.
Rashi
והכית בצור AND THOU SHALT SMITE THE ROCK — It does not say here “thou shalt smite על הצור”, upon the surface of the rock, but בצור, right into the rock — from this it follows that the rod must have been composed of a kind of hard material the name of which is sapphire, and the rock was split by it (Mekhilta).
Chizkuni
בחורב, והכית בצור, although the people were encamped at Refidim, Moses went all the way to Mount Sinai to find the rock that would produce water.
Ramban
BEHOLD, I WILL STAND BEFORE THEE THERE UPON THE ROCK IN HOREB. Since the wonder with the water in this place was now to become a permanent feature as long as they would be in the wilderness, as our Rabbis have said,441See above, Note 436. this was why the Divine Glory was revealed upon it at this place, just as it says concerning the manna, And in the morning, then ye shall see the Glory of the Eternal,442Above, 16:7. since it remained a continuous wonder.