‘Jesus answered and said, “This voice occurred not for my sake, but for your sake”.'
Jesus then explained to them the purpose of the voice from Heaven. It was true that His Father had spoken to Him for His comfort and in response to His yearning, but that could have been said in His heart. It came in the way that it did so that the crowd might recognise that God had spoken to Him. It was important that they should understand the importance of the hour. Compare how in John 11:42 He had prayed aloud for their sakes. All this was preparing the ground for the ministry of the disciples after the resurrection. The hearts of men were being prepared.