A.T. Robertson Commentary Colossians 4

That which is just and equal (το δικαιον κα την ισοτητα). Paul changes from το ισον (like το δικαιον, neuter singular adjective with article for abstract idea) to the abstract substantive ισοτης, old word, in N.T. only here and 2 Corinthians 8:13f. If employers always did this, there would be no labour problem.

A Master in heaven (Κυριον εν ουρανω). A wholesome reminder to the effect that he keeps his eye on the conduct of masters of men here towards their employees.

Continue steadfastly (προσκαρτερειτε). See Mr 3:9; Acts 2:42,46 for this interesting word from προς and καρτερος (strong), common in the Koine.

Watching (γρηγορουντες). Present active participle of γρηγορεω, late present made on perfect active stem εγρηγορα with loss of ε-, found first in Aristotle.

Withal (αμα). At the same time.

That God may open (ινα ο θεος ανοιξη). Common use of ινα and the subjunctive (aorist), the sub-final use so common in the N.T. as in the Koine.

A door for the word (θυραν του λογου). Objective genitive, a door for preaching. It is comforting to other preachers to see the greatest of all preachers here asking prayer that he may be set free again to preach. He uses this figure elsewhere, once of a great and open door with many adversaries in Ephesus (1 Corinthians 16:9), once of an open door that he could not enter in Troas (2 Corinthians 2:12).

The mystery of Christ (το μυστηριον του Χριστου). The genitive of apposition, the mystery which is Christ (2:2), one that puts out of comparison the foolish "mysteries" of the Gnostics.

For which I am also in bonds (δι' ο κα δεδεμα). Perfect passive indicative of δεω. Paul is always conscious of this limitation, this chain. At bottom he is a prisoner because of his preaching to the Gentiles.

As I ought to speak (ως δε με λαλησα). Wonderful as Paul's preaching was to his hearers and seems to us, he was never satisfied with it. What preacher can be?

Toward them that are without (προς τους εξω). A Pauline phrase for those outside the churches (1 Thessalonians 5:12; 1 Corinthians 5:12f.). It takes wise walking to win them to Christ.

Redeeming the time (τον καιρον εξαγοραζομενο). We all have the same time. Paul goes into the open market and buys it up by using it rightly. See the same metaphor in Eph 5:16.