In the game of golf, out-of-bounds or O. B. markers designate when a ball has gone out of play. If a player’s ball goes out-of-bounds, a one-stroke penalty is imposed.
The prophet Jeremiah warned the southern kingdom of Judah about their persistent rejection of God’s boundaries for them. He said that even the sea knows that the sand on the seashore is its O. B. marker, “an everlasting barrier it cannot cross” (Jer. 5:22 NIV).