Verse 5
In singleness of your heart; in faithfulness and honesty.

Verse 8
The same shall he receive of the Lord; that is, though his master might be unjust or oppressive, his fidelity should not ultimately lose its reward.

Verse 9
Do the same things unto them; that is, be honest and upright in all your dealings with them.-- Forbearing threatening; and of course forbearing coercion and violence.

Verse 21
Tychicus. This messenger is also mentioned in the Epistle to the Colossians, (Colossians 4:7,) and is supposed to have been intrusted with both Epistles at the same time.