Continue steadfastly (προσκαρτερειτε). See Mark 3:9; Acts 2:42; Acts 2:46 for this interesting word from προς and καρτερος (strong), common in the Koine.

Watching (γρηγορουντες). Present active participle of γρηγορεω, late present made on perfect active stem εγρηγορα with loss of ε-, found first in Aristotle.