Matthew 17:10

Why then say the scribes?] Jesus, by forbidding the incident to be spoken of (Matthew 17:9), seemed to attach little importance to the present appearance of Elijah. 'Why then,' ask the disciples, 'do the scribes attach so much importance to it? And why are we forbidden to reply to their leading objection to your Messiahship, by saying that Elijah has come, and that we have seen him.' Elias must first come] The Jews expected a personal return of Elijah to prepare the way for the Messiah, not another prophet like him: see on Luke 1:17. It was supposed that his peculiar activity would consist in settling ceremonial and ritual questions, doubts and difficulties, and that he would restore to Israel, (1) the golden pot of manna, (2) the vessel containing the anointing oil, (3) the vessel containing the waters of purification, (4) Aaron's rod that budded and bore fruit.