Matthew 17:10 YLT

⁸  and having lifted up their eyes, they saw no one, except Jesus only.

⁹  And as they are coming down from the mount, Jesus charged them, saying, 'Say to no one the vision, till the Son of Man out of the dead may rise.'

¹⁰  And his disciples questioned him, saying, 'Why then do the scribes say that Elijah it behoveth to come first?'

¹¹  And Jesus answering said to them, 'Elijah doth indeed come first, and shall restore all things,

¹²  and I say to you -- Elijah did already come, and they did not know him, but did with him whatever they would, so also the Son of Man is about to suffer by them.'