Expositor's Bible Commentary Commentary Mark 9:4

"And there appeared unto them Elijah with Moses: and they were talking with Jesus." — Mark 9:4 (ASV)

Why the appearance of Elijah and Moses? If what the disciples saw was a glimpse of Jesus’ final state of glory, then Moses and Elijah’s function is to announce the End. In Jewish expectation, Elijah clearly played that role (cf. Malachi 4:5; Mark 9:11–12). But what of Moses? The possible reappearance of Moses just before the End developed later in Jewish thought. Or Moses and Elijah may have been at the scene as representatives of the Law and the Prophets—i.e., the OT, which was being fulfilled by Jesus.