Knowing that from (the) Lord you will receive the just recompense of the inheritance (Ephesians 6:8; Romans 2:6-11; 2 Corinthians 5:10; Revelation 22:12; Psalms 62:12). "Knowing" ( εἰδότες)—that of which one is aware, not merely learning or "getting to know" ( γινώσκω): see both words in Ephesians 5:5 and John 14:7, Revised Text; also Romans 6:6 and Romans 6:9; 1 John 5:20.
"The absence of the definite article" before κυρίου "is the more remarkable, because it is studiously inserted in the context" (Lightfoot). St. Paul virtually says, "There is a Master who will recompense you, if your earthly masters never do" (comp.
Colossians 4:1). "Just" renders the ἀντὶ in ἀνταπόδοσιν (a word common in LXX), implying "equivalence" or "correspondence" (comp. ἀνταναπληρῶ in Colossians 1:24; also Romans 11:35; Romans 12:19; 1 Thessalonians 3:9; 2 Thessalonians 1:6; Luke 6:38; Luke 14:12, Luke 14:14)—a reward in the case of each individual, and in each particular, answering to the service rendered to "the Lord" (comp.
Matthew 25:14-30). The opposite truth is asserted in verse 25; Ephesians 6:8 combines them both. The recompense of the faithful Christian slave is nothing less than "the inheritance" of God's children (Colossians 1:12; Ephesians 1:5,Ephesians 1:11, Ephesians 1:14; Ephesians 3:6; Ephesians 5:5; Romans 8:17; Galatians 3:29; 1 Corinthians 6:9, 1 Corinthians 6:10; 1 Corinthians 15:50; Titus 3:7; 1 Peter 1:4), which the apostle has so often under other terms assured to his readers (Colossians 1:5, Colossians 1:23, Colossians 1:27; Colossians 2:18; Colossians 3:4, Colossians 3:15).
For a slave to be heir was "a paradox" (Lightfoot): see Galatians 4:1,Galatians 4:7; Romans 8:15-17. No form of praise could be more cheering and ennobling to the despised slave than this. "In Christ," Onesimus is "no longer as a slave, but a brother beloved" (Philippians 1:16), and if a brother, then a joint heir with his master Philemon in the heavenly inheritance (Colossians 3:11).
Ye serve the Lord Christ (Philemon 1:22, Philemon 1:25; Colossians 2:6; Ephesians 6:6; Romans 14:8, Romans 14:9; 1 Corinthians 6:19, 1 Corinthians 6:20; 1 Corinthians 7:22, 1 Corinthians 7:23; John 13:13); that is, Christ is the Lord whose bondmen ye are.
"For" is probably a correct gloss, though a corrupt reading. Its insertion indicates that the sentence was read indicatively (Lightfoot, and R.V.); not imperatively ("serve the Lord Christ"), as Meyer, Alford, Ellicott, with the Vulgate, construe it.
The verse amounts to this: "Work as for the Lord: he will repay you; you are his servants."