Jesus strictly warned them not to tell this to anyone.
In these verses, we have Christ discoursing with his disciples about the great things that pertained to the kingdom of God; and one circumstance of this discourse is taken notice of here which we had not in the other evangelists - that Christ was alone praying, and his disciples with him, when he entered into this discourse, Luk 9:18. Observe, 1.
Commenting on Luke 9:18-27
Saying, the son of man must suffer many things,.... In his person and character, in his soul and body, at the hands of God, and of men, and devils: and be rejected of the elders, and chief priests, and Scribes; who made up the grand sanhedrim of the nation: by these he was to be, and was rejected as the Messiah; and when put up...