Matthew 17:5

The witness of the Father: While he yet spake, behold, a bright cloud overshadowed them; and, behold, a voice out of the cloud, which said, This is My beloved Son, in whom I am well pleased; hear ye Him.

While Peter was still filled with the ecstasy of the scene and describing the beauty of a continuance of the phenomenon, a bright cloud, a cloud of light, surrounded them. As at other times a dark cloud will obscure the light, so here the intense brightness of the cloud of glory hindered their vision; human eyes are not strong enough to endure the light from the throne of heaven. Here was the cloud of the New Testament covering both High Priest and altar of the New Covenant, Exodus 40:24. The disciples had at least, up to that moment, been able to observe a few things, though their vision had not been very clear, but at this climax they are overcome. For the voice of the Father uttered" almost the same words as at the baptism of Jesus: This is My Son, the Beloved One, in whom is My delight. It was a most solemn attestation of Jesus as the Messiah and Son of God, destined to sink into their hearts and minds forever. Him they should hear, to Him, in His Word, they should render unquestioned obedience. The time of the reign of the Law, as represented in Moses, and the time of mere prophecy, as represented in Elijah, was past; grace and truth, the Gospel, the Gospel glory, have come in and with Jesus Christ. No need to look for further visions and revelations; we have the Word of Jesus, the Word of salvation.