Jamieson, Fausset and Brown on Mark 9:31

31. For he taught his disciples, and said unto them--"Let these sayings sink down into your ears" (Lu 9:44); not what had been passing between them as to His grandeur, but what He was now to utter.

The Son of man is delivered--The use of the present tense expresses how near at hand He would have them to consider it. As Bengel says, steps were already in course of being taken to bring it about.

into the hands of men--This remarkable antithesis, "the Son of man shall be delivered into the hands of men," it is worthy of notice, is in all the three Evangelists.

and they shall kill him--that is, "Be not carried off your feet by all that grandeur of Mine which ye have lately witnessed, but bear in mind what I have already told you and now distinctly repeat, that that Sun in whose beams ye now rejoice is soon to set in midnight gloom."

and after he is killed, he shall rise the third day.