John Calvin Commentary Ephesians 6:8

"knowing that whatsoever good thing each one doeth, the same shall he receive again from the Lord, whether [he be] bond or free." — Ephesians 6:8 (ASV)

Knowing that whatsoever good thing any man doeth. What a powerful consolation! However unworthy, however ungrateful or cruel, their masters may be, God will accept their services as rendered to himself. When servants take into account the pride and arrogance of their masters, they often become more indolent from the thought that their labor is thrown away. But Paul informs them that their reward is laid up with God for services which appear to be ill bestowed on unfeeling men, and that there is no reason, therefore, why they should be led aside from the path of duty.

He adds, whether bond or free. No distinction is made between a slave and a free man. The world tends to set little value on the labors of slaves, but God esteems them as highly as the duties of kings. In his estimate, the outward station is thrown aside, and each is judged according to the uprightness of his heart.