Ephesians 6:5-6

6:5 Slaves, obey your human masters with fear and trembling, in the sincerity of your heart as to Christ, 6:6 not like those who do their work only when someone is watching – as people-pleasers – but as slaves of Christ doing the will of God from the heart.

Colossians 3:22

3:22 Slaves, obey your earthly masters in every respect, not only when they are watching – like those who are strictly people-pleasers – but with a sincere heart, fearing the Lord.

Titus 2:9

2:9 Slaves are to be subject to their own masters in everything, to do what is wanted and not talk back,