Exodus 17:5

Overview - Exodus 17
1	The people murmur for water at Rephidim.
6	God sends them for water to the rock in Horeb.
7	The place is called Massah and Meribah.
8	Amalek is overcome by Joshua, while Moses holds up his hands with the rod of God.
14	Amalek is doomed to destruction; and Moses builds the altar JEHOVAH-nissi.

Exodus 17:5  (King James Version)
And the LORD said unto Moses, Go on before the people, and take with thee of the elders of Israel; and thy rod, wherewith thou smotest the river, take in thine hand, and go.