Mark 9:10

And they kept the saying, questioning among themselves what the rising again from the dead should mean.

And they kept the saying ... means that the three apostles obeyed the Saviour's injunction of secrecy.

Questioning ... The resurrection of Christ was an event utterly beyond the comprehension of the apostles because: (1) of the inherent preconditioning of the human race not to expect any such thing; (2) of the false idea they had concerning the Messiah and what he would do on earth; and (3) of their failure, at first, to believe Jesus' prophecies of his impending death. Commentators who themselves will not even believe the resurrection of Christ after the event are in a very sorry role when they criticize the apostles for their failure to believe it before the fact.