Isaiah 21:6

For thus hath the Lord said unto me
This is a confirmation of the above prophecy from the Lord himself, he showing to the prophet, in a visionary way, the ruin of Babylon, and the means and instruments of it: go, set a watchman;
not Habakkuk, as Jarchi; nor Urias, as the Septuagint; nor Jeremiah, as others; but himself, who, in a way of vision, represented a watchman on the walls of Babylon; and which was no way unsuitable to his character and office as a prophet: let him declare what he seeth;
what he sees coming at a distance, or at hand, let him faithfully and publicly make it known: these are not the words of the king of Babylon to one of his watchmen; but of the Lord of hosts to his prophet.