How can you tell the disciples did not understand that Jesus would be raised from the dead?
The disciples did not understand because the saying was hidden from them and they understood none of these things. Jesus had told them He would rise, but God had not opened their eyes. Had they understood, they would have waited outside the tomb Sunday morning.
Les explains that although Jesus told the disciples more than once He was going to be crucified and rise from the dead, God never opened their eyes to it. The text says the saying was hidden from them, and they understood none of these things. So when Jesus was crucified, not one of the eleven expected Him back among the living on Sunday morning. Les illustrates that if they had understood He was going to be raised, they would have been outside the tomb waiting to see it happen. The resurrection-morning account in John 20 confirms this: Mary Magdalene came to anoint the corpse, found the body gone, and concluded someone had stolen it; Peter and John ran to the sepulcher rather than waiting in expectation.