'Watchman's' in the Bible

The daughter of Zion is left like a shelter in a vineyard,Like a watchman’s hut in a cucumber field, like a besieged city.

But if the watchman sees the sword coming and does not blow the trumpet and the people are not warned, and a sword comes and takes a person from them, he is taken away in his iniquity; but his blood I will require from the watchman’s hand.’