Jamieson, Fausset and Brown on Daniel 9:21

21. I had seen in the vision at the beginning--namely, in the former vision by the river Ulai (Da 8:1, 16).

fly swiftly--literally, "with weariness," that is, move swiftly as one breathless and wearied out with quick running [Gesenius]. English Version is better (Is 6:2; Eze 1:6; Re 14:6).

time of ... evening oblation--the ninth hour, three o'clock (compare 1Ki 18:36). As formerly, when the temple stood, this hour was devoted to sacrifices, so now to prayer. Daniel, during the whole captivity to the very last, with pious patriotism never forgot God's temple-worship, but speaks of its rites long abolished, as if still in use.