“…love dwells nowhere but in the heart, indeed, in the innermost center of the heart, and for this reason there is that difference between [His children] and bond servants, because [His children] serve Him, not in fear of punishment or desire or glory, but only to fulfill the will of God; but the bond servants are forced by fear of punishment, and they serve Him unwillingly and with great difficulty, or they are desirous of a reward, in which case they serve him with a mercenary intent, but never absolutely out of a desire to fulfill His will.  Particularly in time of tribulation does the servant and hireling run away, but [His child] perseveres….”

Lectures on Roman