While he yet spake, behold, a bright cloud overshadowed them: and behold a voice out of the cloud, which said, This is {c} my beloved Son, in whom I am well pleased; hear ye him.

(c) The word my distinguishes Christ from other children. For he is God's natural son, we by adoption; therefore he is called the first begotten among the brethren, because although he is by right the only son, yet he is chief among many, in that he is the source and head of the adoption.

People's New Testament

17:5 A bright cloud overshadowed them. Christ, Moses and Elijah are represented as in the cloud which separated them from the disciples' sight; and out of this cloud the voice spoke to the disciples. By the disciples such a luminous cloud would be instantly accepted as a symbol of Divine presence. A bright cloud, the Shekinah, is throughout the Old Testament dispensation employed as a symbol of God's presence, being very generally entitled the glory, or the glory of the Lord. (See, for example, Ex 16:10 19:09 24:16,17.)

This is my beloved Son. The same voice which had once before been heard at the baptism. Such a confirmation of the great confession of Peter was never to be forgotten. Almost a generation later, when he wrote his second epistle, the remembrance of this night was as vivid as ever: For he received from God the Father honor and glory, when there came such a voice to him from the excellent glory (2Pe 1:17).

Hear ye him. The Divine voice that spoke at Sinai and the baptism is heard, declaring Christ's superiority to Moses and Elijah, in that he is the beloved Son, and commanding all to Hear Him. Henceforth, not Moses, or Elijah, are the lawgivers of the people of God, but Christ. The saints are bidden to turn from every human teacher, even those as revered as Moses and Elijah, to listen to our Lord. To hear Him will lead from error and sin into truth, righteousness and fitness for heaven.

Wesley's Notes

17:5 Hear ye him - As superior even to Moses and the prophets. See Deut 18:17.

Matthew Henry's Concise Commentary

17:1-13 Now the disciples beheld somewhat of Christ's glory, as of the only begotten of the Father. It was intended to support their faith, when they would have to witness his crucifixion; and would give them an idea of the glory prepared for them, when changed by his power and made like him. The apostles were overcome by the glorious sight. Peter thought that it was most desirable to continue there, and to go no more down to meet the sufferings of which he was so unwilling to hear. In this he knew not what he said. We are wrong, if we look for a heaven here upon earth. Whatever tabernacles we propose to make for ourselves in this world, we must always remember to ask Christ's leave. That sacrifice was not yet offered, without which the souls of sinful men could not have been saved; and important services were to be done by Peter and his brethren. While Peter spoke, a bright cloud overshadowed them, an emblem of the Divine presence and glory. Ever since man sinned, and heard God's voice in the garden, unusual appearances of God have been terrible to man. They fell prostrate to the earth, till Jesus encouraged them; when looking round, they beheld only their Lord as they commonly saw him. We must pass through varied experiences in our way to glory; and when we return to the world after an ordinance, it must be our care to take Christ with us, and then it may be our comfort that he is with us.