Psalms 114:8
Ver. 8. Which turned the rock into a standing water,.... Both at Rephidim and at Kadesh; which being smitten, streams of water flowed out like rivers, as if the rock itself was changed into water; and which came a constant and continual supply for the Israelites, for it is said to follow them; see Ex 17:6.
The flint into a fountain of waters; referring to the same thing, the rocks were flinty ones. This was a type of Christ the Rock; who has an abiding fulness of grace in him; is the fountain of it, from whence it flows in great abundance for the supply of his people's wants, while passing through this wilderness to Canaan's land.
John Gill's Exposition of the Entire Bible.