Those who have believing masters, let them not despise them, because they are brothers, but rather let them serve them, because those who partake of the benefit are believing and beloved. Teach and exhort these things.
The use of the word "rather" contrasts "let them not despise them" and "do them service." Instead of using their spiritual relationship as a basis for less devotion, they should use it as a motivation for greater devotion. (See Ephesians 5:4.) As MacKnight paraphrases, "Wherefore, let them serve their masters more diligently, because they who enjoy the benefit of their services are believers and beloved of God" (462).