Albert Barnes Commentary Daniel 8:26

"And the vision of the evenings and mornings which hath been told is true: but shut thou up the vision; for it belongeth to many days [to come]." — Daniel 8:26 (ASV)

And the vision of the evening and the morning - That is, of the two thousand three hundred days. See Daniel 8:14, and the margin on that verse. The meaning here is, “the vision pertaining to that succession of evenings and mornings.” Perhaps this name was given to it particularly because it pertained so much to the evening and morning sacrifice.

Is true - This shall be certainly accomplished. This was said by the angel, thus giving Daniel the assurance that what he had seen (Daniel 8:9–14) was no illusion, but would certainly come to pass.

Wherefore shut thou up the visions - Seal it up. Make a record of it, so that it may be preserved, and so that its fulfillment may be marked. See the notes at Isaiah 8:16.

For it shall be for many days - That is, many days will elapse before it will be accomplished. Therefore, let a clear record be made of it, and let it be sealed up, so that it may be preserved to prepare the people for these events. “When” these things would come so fearfully upon the people of Judea, they would be better able to bear these trials, knowing the period when they would end.