'Watchman' in the Bible

And David is sitting between the two gates, and the watchman goeth unto the roof of the gate, unto the wall, and lifteth up his eyes, and looketh, and lo, a man running by himself.

And the watchman calleth, and declareth to the king, and the king saith, 'If by himself, tidings are in his mouth;' and he cometh, coming on and drawing near.

And the watchman seeth another man running, and the watchman calleth unto the gatekeeper, and saith, 'Lo, a man running by himself;' and the king saith, 'Also this one is bearing tidings.'

And the watchman saith, 'I see the running of the first as the running of Ahimaaz son of Zadok.' And the king saith, 'This is a good man, and with good tidings he cometh.'