Job 14:19 NKJV
As water wears away stones, And as torrents wash away the soil of the earth; So You destroy the hope of man.
Job mentions water wearing away stones as he speaks to God while enduring great misery. He misunderstood God but he displayed a little knowledge about nature in his conversation. Because of the constant flow of water over them, rocks on the beach or in a stream are made smooth. The moving water removes their rough edges and produce what we call pebbles. Rough edges on stones make them more harmful than smooth stones.
Spiritual parallel: There are rough edges in all our lives. The more rough edges we have, the greater the potential of hurting others. In the book of Psalms we find several references to a sharp tongue in the context of people hurting others. Just as natural water helps get rid of sharp or rough edges, the water of the Word and the Spirit can help us get rid of the rough and sharp edges in our lives, particularly our mouths. The speed in which a pebble develops depends on the speed of the current running over it. The greater the force, the faster the pebble is created. If our rough edges seem to take too long to become smooth, we need to increase the force of the Word and the Spirit in our lives. We can increase the force by letting the spiritual water wash us over and over, back to back, and lifting up our voices to forcefully agree with the Word we hear.