Matthew 17:9

μηδενὶ εἴπητε : injunction of secrecy. The reason of the injunction lies in the nature of the experience. Visions are for those who are prepared for them. It boots not to relate them to those who are not fit to receive them. Even the three were only partially fit; witness their terror (Matthew 17:6). τὸ ὅραμα, the vision, justifying the view above given of the experience, held, among others, by Elsner, Herder, Bleek and Weiss. Herder has some fine remarks on the analogy between the experiences of Jesus at His baptism and on the Mount, six days after the announcement at Caesarea Philippi, and those of other men at the time of moral decisions in youth and in the near presence of death (vide his Vom Erlöser der Menschen, §§ 18, 19). ἕμς οὗ, followed by subjunctive without ἄν; in this case (cf. Matthew 16:28) one of future contingency at a past time. The optative is used in classics (vide Burton, § 324). Not till the resurrection. It is not implied that Jesus was very desirous that they should then begin to speak, but only that they could then speak of the vision intelligently and intelligibly. Christ's tone seems to have been that of one making light or the recent experience (as in Luke 10:20).