“After all we can do” (2 Nephi 25:23) and Origen

"For when we have done all that is within our power, God will make up whatever is lacking through our human weakness as he works together with those who love him for good in all things [Romans 8:28]"
(Origen, ca. 233, 'On Prayer' 29:19, in 'Popular Patristics' 29:204)

(My thanks for Errol Amey for making me aware of this passage from Origen of Alexandria)