'Watchman' in the Bible

Now Absalom had fled. And the young man who was the watchman raised his eyes and looked, and behold, many people were coming from the road behind him by the side of the mountain.

Now David was sitting between the two gates; and the watchman went up to the roof of the gate by the wall, and raised his eyes and looked, and behold, a man running by himself.

The watchman called and told the king. And the king said, “If he is by himself there is good news in his mouth.” And he came nearer and nearer.

Then the watchman saw another man running; and the watchman called to the gatekeeper and said, “Behold, another man running by himself.” And the king said, “This one also is bringing good news.”

The watchman said, “I think the running of the first one is like the running of Ahimaaz the son of Zadok.” And the king said, “This is a good man and comes with good news.”