Jamieson, Fausset and Brown on 2 Samuel 23:3

3. the Rock of Israel--This metaphor, which is commonly applied by the sacred writers to the Almighty, was very expressive to the minds of the Hebrew people. Their national fortresses, in which they sought security in war, were built on high and inaccessible rocks.

spake to me--either preceptively, giving the following counsels respecting the character of an upright ruler in Israel, or prophetically, concerning David and his royal dynasty, and the great Messiah, of whom many think this is a prophecy, rendering the words, "he that ruleth"--"there shall be a ruler over men."