Mat 17:7 Arise, and be not afraid.

The reaction of the apostles to the transfiguration when they heard God's voice was to fall down and tremble. Here, Christ is telling them that this reaction is wrong.

"Arise" is from egeirô, which means "awaken," "rouse," and "stip up." This is the term used in the NT to describe people getting up from their beds or even graves. It also describes nations and people rising up in rebellion.

"Afraid" is from phobeô, wihch means "to be put to flight," "to fear," and "to be afraid."