John Calvin Commentary Colossians 4:2

"Continue stedfastly in prayer, watching therein with thanksgiving;" — Colossians 4:2 (ASV)

Continue in prayer. He returns to general exhortations, in which we should not expect an exact order; for in that case, he would have begun with prayer, but Paul did not have that in view. Furthermore, regarding prayer, he commends two things here: first, diligence; secondly, eagerness, or earnest attentiveness. For when he says, continue, he exhorts to perseverance, while he mentions watching in opposition to coldness and listlessness.

He adds, thanksgiving, because God must be petitioned for present needs in such a way that, meanwhile, we do not forget favors already received. Furthermore, we should not be so troublesomely persistent as to murmur and feel offended if God does not immediately grant our wishes, but we must receive contentedly whatever he gives. Thus, a twofold giving of thanks is necessary. Regarding this point, something has also been said in the Epistle to the Philippians (Philippians 4:6).