'Watchman' in the Bible

For thus hath the Lord said unto me, Go, set a watchman: let him declare what he seeth:

The burden of Dumah. One calleth unto me out of Seir, Watchman, what of the night? Watchman, what of the night?

The watchman said, The morning cometh, and also the night: if ye will inquire, inquire ye: turn ye, come.