Mark 9:11-13

11 Then they asked him, "Why do the scribes say that Elijah must come first?"
12 He said to them, "Elijah is indeed coming first to restore all things. How then is it written about the Son of Man, that he is to go through many sufferings and be treated with contempt?
13 But I tell you that Elijah has come, and they did to him whatever they pleased, as it is written about him."

Mark 9:11-13 In-Context

9 As they were coming down the mountain, he ordered them to tell no one about what they had seen, until after the Son of Man had risen from the dead.
10 So they kept the matter to themselves, questioning what this rising from the dead could mean.
11 Then they asked him, "Why do the scribes say that Elijah must come first?"
12 He said to them, "Elijah is indeed coming first to restore all things. How then is it written about the Son of Man, that he is to go through many sufferings and be treated with contempt?
13 But I tell you that Elijah has come, and they did to him whatever they pleased, as it is written about him."
14 When they came to the disciples, they saw a great crowd around them, and some scribes arguing with them.
15 When the whole crowd saw him, they were immediately overcome with awe, and they ran forward to greet him.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.