John Calvin Commentary Colossians 4:6

"Let your speech be always with grace, seasoned with salt, that ye may know how ye ought to answer each one." — Colossians 4:6 (ASV)

Your speech. He requires graciousness of speech, that may attract hearers by its benefit, for he does not merely condemn communications that are openly wicked or ungodly, but also those that are worthless and idle. Therefore, he would have them seasoned with salt. Worldly people have their own ways of seasoning conversation, but he is not speaking of those; indeed, since witticisms are persuasive and generally gain favor, he indirectly prohibits believers from the practice and familiar use of them. For he considers everything that does not edify to be tasteless. The term grace is used in the same sense, as opposed to talkativeness, taunts, and all kinds of trivial matters that are either harmful or pointless.

That you may know how. The person who has accustomed himself to caution in his communications will not fall into many absurdities, which talkative and chattering persons fall into from time to time, but, through constant practice, will acquire for himself skill in making proper and suitable replies. On the other hand, it inevitably happens that foolish talkers expose themselves to ridicule whenever they are questioned about anything; and in this, they pay the just punishment for their foolish talkativeness. Nor does he merely say what, but also how, and not to all indiscriminately, but to every one. For this is not the least important part of wisdom—to give proper consideration to individuals.