Albert Barnes Commentary Daniel 2:19

"Then was the secret revealed unto Daniel in a vision of the night. Then Daniel blessed the God of heaven." — Daniel 2:19 (ASV)

Then was the secret revealed ... - That is, the dream and the interpretation. The thing which had been "hidden" was disclosed. We may suppose that this occurred after a suitable time had been given to prayer.

In a night vision - A representation made to him at night, but whether he was asleep or awake does not appear. Compare the notes at Daniel 1:17, Isaiah 1:1, Job 4:13, and Job 33:15.

Then Daniel blessed the God of heaven - Nothing would be more natural than for him to burst forth in a song of grateful praise for the disclosure of a secret. Through this disclosure, his life and the lives of his companions would be preserved, and such signal honor would accrue to God Himself, as the only one able to reveal coming events.