Matthew 17:10-13

10The disciples asked him, “Why then do the teachers of the law say that Elijah must come first?” 11Jesus replied, “To be sure, Elijah comes and will restore all things. 12But I tell you, Elijah has already come, and they did not recognize him, but have done to him everything they wished. In the same way the Son of Man is going to suffer at their hands.” 13Then the disciples understood that he was talking to them about John the Baptist.