Charles H. Spurgeon on Psalms 114:8

The same almighty power that turned waters into a rock to be a wall to Israel (Ex 14:22), turned the rock into waters to be a well to Israel. As they were protected, so they were provided for, by miracles, standing miracles; for such was the standing water, that fountain of waters, into which the rock, the flinty rock, was turned, "and that rock was Christ, "1Co 10:4. For he is a fountain of living waters to his Israel, from whom they receive grace for grace. —Matthew Henry.