Jamieson, Fausset and Brown on Mark 9:32

32. But they understood not that saying--"and it was hid from them, [so] that they preceived it not" (Lu 9:45).

and were afraid to ask him--Their most cherished ideas were so completely dashed by such announcements, that they were afraid of laying themselves open to rebuke by asking Him any questions. But "they were exceeding sorry" (Mt 17:23). While the other Evangelists, as Webster and Wilkinson remark, notice their ignorance and their fear, Matthew, who was one of them, retains a vivid recollection of their sorrow.

Mr 9:33-50. Strife among the Twelve Who Should Be Greatest in the Kingdom of Heaven, with Relative Teaching--Incidental Rebuke of John for Exclusiveness. ( = Mt 18:1-9; Lu 9:46-50).

Strife among the Twelve, with Relative Teaching (Mr 9:33-37).