A.T. Robertson Commentary Luke 9:37

"And it came to pass, on the next day, when they were come down from the mountain, a great multitude met him." — Luke 9:37 (ASV)

On the next day (τη εξης ημερα). Alone in Luke. It shows that the Transfiguration took place on the preceding night.

They were come down (κατελθοντων αυτων). Genitive absolute of second aorist active participle of κατερχομα, a common enough verb, but in the N.T. only in Luke's writings save Jas 3:15.

Met him (συνηντησεν αυτω). First aorist active of συνανταω, common compound verb, to meet with, only in Luke's writings in the N.T. save Heb 7:1. With associative instrumental case αυτω.