John Gill Commentary Mark 16:4

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

And when they looked
Towards the sepulchre, as they came near it:

they saw that the stone was rolled away ;
they perceived it lay at some distance from the door of the sepulchre, which doubtless was very grateful, and matter of rejoicing to them:

for it was very great ;
these words are to be read, in connection with the preceding verse; for they are not a reason, why when they looked towards the sepulchre, they saw the stone rolled, because it was a very large one, and so easily to be seen at a distance; but a reason why they were so thoughtful and concerned, who should roll it away for them, it being so big, that they could not think that they were able to do it themselves.