The Mighty Angel [Christ] called the Two Witnesses, My Two Witnesses implying that witnessing was their mission.

         When they witnessed on the Mt of Transfiguration and Two Men witnessed at the Tomb that Jesus had risen and it was Two Men who stood by and witnessed to the Disciples as Jesus ascended into Heaven.  In all three incidents the Men were clothed in shining garments.

                It seems that Moses was resurrected and Elijah translated for the purpose of Witnessing.