προσκαρτερέω
proskarteréō
pros-kar-ter-eh'-o
Greek: Verb
from πρός and καρτερέω; to be earnest towards, i.e. (to a thing) to persevere, be constantly diligent, or (in a place) to attend assiduously all the exercises, or (to a person) to adhere closely to (as a servitor).

KJV translates as: attend (give self) continually (upon), continue (in, instant in, with), wait on (continually)