“And as they came down from the mountain, he charged them that they should tell no man what things they had seen, till the Son of man were risen from the dead.”
Mark 9:9 — Greek Interlinear
Church Fathers on Mark 9:9
After the shewing of the mystery on the mount, the Lord commanded His disciples, as they were coming down from the mount, not to reveal His transfiguration, before the glory of His Passion and Resurrection.
Which He did lest men should be offended, hearing such glorious things of Him Whom they were about to see crucified. It was not therefore fitting to say such things of Christ before He suffered, but after His resurrection they were likely to be believed.
This, which is peculiar to Mark, means, that when death shall have been swallowed up in victory, we shall have no memory for the former things.