Bond-servants, obey your masters according to the flesh. There were many slaves in the early Church, but, however unjust their position, the apostle could not but counsel them to obedience, this course being the best for ultimately working out their emancipation.
The words of Christ were peculiarly welcome to them "that labor and are heavy laden;" and, as we find from Celsus and others, the early Church was much ridiculed for the large number of uneducated persons in its pale.
With fear and trembling. Comp. 1 Corinthians 2:3; Philippians 2:12, from which it will be seen that this expression does not denote slavish dread, but great moral anxiety lest one should fail in duty.
It was probably a proverbial expression. In the singleness of your heart, as to Christ. Not with a got-up semblance of obedience, but with inward sincerity, knowing that it is your duty; and even if it be irksome, doing it pleasantly, as though Christ required it, and you were doing it to him.