Charles Ellicott Commentary Mark 16:4

"and looking up, they see that the stone is rolled back: for it was exceeding great." — Mark 16:4 (ASV)

For it was very great.—The words have been explained as giving the reason for their previous question, but it seems more natural to see in them St. Mark’s explanation of his having used the word “rolled away” instead of saying, simply, “taken away” or “removed.”