Mark saith the same, Mark 9:9. Luke saith, Luke 9:36, They kept it close, and told no man in those days any of those things which they had seen. The other two evangelists record the precept; Luke and Mark, their obedience to it. The most probable reason of this charge given by interpreters is, lest his after sufferings should have shaken again their faith, as to the Divine nature of Christ, before he was by his resurrection from the dead declared to be the Son of God with power, as the apostle speaks, Romans 1:4.
Related Commentaries of Matthew 17:9
Matthew 17:9
9 And as they came down from the mountain, Jesus charged them, saying,Tell the vision to no man, until the Son of man be risen again from the dead.