Daniel 7:1

The date of this chapter places it before ch. 5, which was in the last year of Belshazzar, and ch. 6, which was in the first of Darius; for Daniel had those visions in the first year of Belshazzar, when the captivity of the Jews in Babylon was drawing near a period. Belshazzar's name here is, in the original, spelt differently from what it used to be; before it was Bel-she-azar - Bel is he that treasures up riches. But this is Bel-eshe-zar - Bel is on fire by the enemy. Bel was the god of the Chaldeans; he had prospered, but is now to be consumed. We have, in these verses, Daniel's vision of the four monarchies that were oppressive to the Jews. Observe, I. The circumstances of this vision. Daniel had interpreted Nebuchadnezzar's dream, and now he is himself honoured with similar divine discoveries (Dan 7:1): He had visions of his head upon his bed, when he was asleep; so God sometimes revealed himself and his mind to the children of men, when deep sleep fell upon them (Job 33:15); for when we are most retired from the world, and taken off from the things of sense, we are most fit for communion with God.

— Matthew Henry's Concise Commentary (public domain)