Horeb

Now Moses fed the sheep of Jethro, his father in law, the priest of Madian: and he drove the flock to the inner parts of the desert, and came to the mountain of God, Horeb.

Behold I will stand there before thee, upon the rock Horeb, and thou shalt strike the rock, and water shall come out of it that the people may drink. Moses did so before the ancients of Israel.