Adam Clarke on Daniel 9:3

I set my face - to seek by prayer - He found that the time of the promised deliverance could not be at any great distance; and as he saw nothing that indicated a speedy termination of their oppressive captivity, he was very much afflicted, and earnestly besought God to put a speedy end to it; and how earnestly he seeks, his own words show. He prayed, he supplicated, he fasted, he put sackcloth upon his body, and he put ashes upon his head. He uses that kind of prayer prescribed by Solomon in his prayer at the dedication of the temple. See 1Kgs 8:47, 1Kgs 8:48.