Albert Barnes Commentary Colossians 4:3

"withal praying for us also, that God may open unto us a door for the word, to speak the mystery of Christ, for which I am also in bonds;" — Colossians 4:3 (ASV)

Withal. With all the supplications that you offer for other persons and things; or at the same time that you pray for them.

Praying also for us (or, "praying at the same time"). See Barnes on Ephesians 6:19-20.

Compare 2 Corinthians 1:11; Philippians 1:19; Hebrews 13:18–19.

That God would open to us a door of utterance (compare 2 Thessalonians 3:1). This means a door to preach the gospel. He earnestly desired to have liberty to preach the gospel and asked them to pray that this might be restored to him. See Barnes on Ephesians 6:19.

To speak the mystery of Christ. This is called the mystery of the gospel in Ephesians 6:19. See Barnes on Ephesians 6:19.

For which I am also in bonds. That is, a prisoner at Rome. See Barnes on Ephesians 6:20.