“As they were coming down
The mountain,
Jesus instructed them.
‘Tell no one
This vision,
Until the Son of Man
Has been raised
From the dead.’”
Καὶ καταβαινόντων αὐτῶν ἐκ τοῦ ὄρους ἐνετείλατο αὐτοῖς ὁ Ἰησοῦς λέγων Μηδενὶ εἴπητε τὸ ὅραμα ἕως οὗ ὁ Υἱὸς τοῦ ἀνθρώπου ἐκ νεκρῶν ἐγερθῇ.
Once again, we are back at the messianic secret that can be found in all 3 synoptic gospels, Mark, chapter 9:9, Luke, chapter 9:36, and here in Matthew that is closer to Mark. Jesus and his 3 disciples came down or descended from the mountain (Καὶ καταβαινόντων αὐτῶν ἐκ τοῦ ὄρους). He commanded, instructed, or ordered them (νετείλατο αὐτοῖς ὁ Ἰησοῦς λέγων) not to tell anyone about this spectacular vision (Μηδενὶ εἴπητε τὸ ὅραμα) until the Son of Man had been raised from the dead (ἕως οὗ ὁ Υἱὸς τοῦ ἀνθρώπου ἐκ νεκρῶν ἐγερθῇ). They would be free to speak about this after the death and resurrection of Jesus, but not before that turning point among the followers of Jesus.