{Wherefore watch ye} (dio gr(8867)oreite). Paul has concluded
his defence of himself and his warning. Now he exhorts on the
basis of it (dio) because of which thing. The very command of
Jesus concerning the perils before his return as in  Mr 13:35 
(gr(8867)oreite), the very form (late present imperative from the
second perfect egr(8867)ora of egeir(935c), to arouse). Stay awake. {I
ceased not to admonish} (ouk epausam(886e) nouthet(936e)). Participle
describes Paul, I did not cease admonishing, night and day
(
ukta kai h(886d)eran, accusative of extent of time, for three
years 	rietian, accusative of extent of time also). Nouthet(936e)
is from 
outhete(935c), to put sense into one. So Paul kept it up
with tears (verse  19 ) if so be he could save the Ephesians from
the impending perils. Forewarned is to be forearmed. Paul did his
duty by them.