John Gill Commentary Luke 9:36

"And when the voice came, Jesus was found alone. And they held their peace, and told no man in those days any of the things which they had seen." — Luke 9:36 (ASV)

And when, the voice was past
The above words were delivered, and it was heard no more: Jesus was found alone; by his disciples; Moses and Elias being gone, and he in the same form in which he was before his transfiguration.

And they kept it close ;
as Christ strictly charged them, when coming down from the mount with them; (Matthew 17:9) .

And told no man in those days any of those things which they had seen ;
no, not any of their fellow disciples, until that Christ was risen from the dead.