As they were coming down the mountain, Jesus admonished them not to tell anyone what they had seen until the Son of Man had risen from the dead.

Matthew 8:4
Then Jesus instructed him, "See that you don't tell anyone. But go, show yourself to the priest and offer the gift prescribed by Moses, as a testimony to them."

Matthew 17:9
As they were coming down the mountain, Jesus commanded them, "Do not tell anyone about this vision until the Son of Man has been raised from the dead."

Mark 5:43
Then Jesus gave strict orders that no one should know about this, and He told them to give her something to eat.

Mark 7:36
Jesus ordered them not to tell anyone. But the more He ordered them, the more widely they proclaimed it.

Mark 8:30
And Jesus warned them not to tell anyone about Him.

Mark 9:8
Suddenly, when they looked around, they saw no one with them except Jesus.

Mark 9:10
So they kept this matter to themselves, discussing what it meant to rise from the dead.

Luke 9:36
After the voice had spoken, only Jesus was present with them. The disciples kept this to themselves, and in those days they did not tell anyone what they had seen.

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.