Charles Ellicott Commentary Luke 9:31

"who appeared in glory, and spake of his decease which he was about to accomplish at Jerusalem." — Luke 9:31 (ASV)

Spake of his decease.—St. Luke's is the only narrative that names the subject of the words that passed between our Lord and Moses and Elias. The use of the word “decease” (exodos) instead of “death” is remarkable for the following reasons:

1. It had not been commonly so used by Greek authors.
2. In its wider range of meaning, it covered all the special phenomena connected with the close of the ministry of the Lawgiver and the Tishbite (2 Kings 2:11), and not less so, the Resurrection and Ascension of our Lord, as well as the Crucifixion.
3. It is also found in close connection with a reference to the Transfiguration in 2 Peter 1:15.

Which he should accomplish.—Literally, which He was about to accomplish.