'Rock' in the Bible

He is like a man building a house, who dug and went deep, and laid a foundation on the rock. When a flood arose, the stream broke against that house, and could not shake it, because it was founded on the rock.

Other seed fell on the rock, and as soon as it grew, it withered away, because it had no moisture.

Those on the rock are they who, when they hear, receive the word with joy; but these have no root, who believe for a while, then fall away in time of temptation.