Matthew 17:10-13

10 And the disciples asked him, "Why, then, do the scribes say that Elijah must come first?"

11 He replied, "Elijah is indeed coming and will restore all things;

12 but I tell you that Elijah has already come, and they did not recognize him, but they did to him whatever they pleased. So also the Son of Man is about to suffer at their hands."

13 Then the disciples understood that he was speaking to them about John the Baptist.