9 I saw until thrones were placed, and one who was ancient of days sat: his clothing was white as snow, and the hair of his head like pure wool; his throne was fiery flames, [and] the wheels of it burning fire.
I watched til thrones were put in place – these will be explained in Dan 7:26, and Rev 20:4. These are the thrones of the Martyrs who judge Babylon. They speak for the truth by their blood. At this point, the thrones are only being “put in place.” The martyrs have yet to sit on them, which occurs in verse 10, “the court was seated.” These thrones are being set up as the martyrs are killed, and so this prophecy begins with the Roman persecution of the saints.
the Ancient of Days – this is Christ as the image of the invisible God, as revealed in Rev 1:14.
His garment as white as snow – see Rev 1:14, “as white as snow.”
hair…like pure wool – see Rev 1:14, “his head and hair a pure wool;” this imagery repeated in Revelation tells us that the Spirit of Christ was the “image of the invisible God” in Daniel.
His throne a fiery flame – see Ezek 1:27, the appearance of Christ, as God on His throne.
Its wheels a burning fire – here, Daniel sees the wheels of the living creatures around the throne, that we first saw in Ezek 1:16-21. The writer of Hebrews describes God as “a consuming fire,” (Heb 12:29).