Mark 9:4

9:4 Then Elijah appeared before them along with Moses, ¹  and they were talking with Jesus.

Mark 15:35

15:35 When some of the bystanders heard it they said, “Listen, he is calling for Elijah!” ² 

[9:4]  ¹ sn Commentators and scholars discuss why Moses and Elijah are present. The most likely explanation is that Moses represents the prophetic office (Acts 3:18-22) and Elijah pictures the presence of the last days (Mal 4:5-6), the prophet of the eschaton (the end times).

[15:35]  ² sn Perhaps the crowd thought Jesus was calling for Elijah because the exclamation “my God, my God” (i.e., in Aramaic, Eloi, Eloi) sounds like the name Elijah.