Let no corrupt word go out of your mouth, but if [there be] any good one for needful edification, that it may give grace to those that hear [it].
This verse puts a test on everything we say. The question is not just whether a word is clean, but whether it builds someone up and leaves grace with the person who hears it.
Wider than foul language
William Kelly reads the verse as covering a whole class of talk that most people would call harmless:
Throw worthless language away as you would throw away spoiled fruit. If such a word is on your tongue, let it go no further. Unclean talk we will find named and forbidden in the next chapter. Here I think the circle is wider. Many people would never speak or listen to dirty talk. Yet they often have to grieve over talk that does no good, and over those who approve it. It is better to say nothing than to speak when there is nothing good to build others up.
Two natures, two kinds of speech
Darby asks which of two natures is doing the talking:
Here we see the contrast between the old self and the new. One or the other speaks: either it complains, or it gives thanks. The mature Christian would only speak to build others up. The new self, moved by the Spirit, will only take part in what builds up.
Measured by the need in front of you
"As fits the occasion" adds a second filter after "good." A word can pass the first test and still fail the second:
The point is not only that corrupt talk stops. Positive good comes out — words that build up according to the need. Not only good language, but good for the occasion, and this assumes the Holy Spirit's power. We have often said things that were good in themselves but not needed at the time. I once saw a man give away food and medicines. The gifts were excellent, but he paid no attention to what the people receiving them actually needed.
Kelly draws the practical rule from the same clause: "The need measures the service, and love builds up instead of puffing up as knowledge does."
No neutral words
A. Pridham gives a test for what we say, and warns that talk which does not build up does harm:
Christian conversation calls for a constant remembrance that God is present. That memory holds back the outbursts of our sinful nature. Nothing that we cannot say with confidence in that presence is fit for the ears of one another. We would do well to remember that if our words do not edify, they are harmful. Whatever does not have the flavour of Christ has the flavour of the world. Talk like that does not strengthen God's building; it pulls it down.
Grace received, grace given
T. B. Baines points to Christ Himself as the pattern:
It is not enough for the believer to avoid corrupt talk. That kind of talk belongs to "the old self, which belongs to your former manner of life and is corrupt through deceitful desires." The believer has put on the new self, and Christ is its perfect pattern. Did Christ merely refrain from evil in His conversation? No; His words, like His life, gave grace to those who heard. And so will the words of one who is in communion with Christ.
Why the next verse follows
W. T. P. Wolston shows what careless talk does to the Holy Spirit:
If we walk carelessly, letting corrupt talk come out of our mouth, we will by that very thing grieve the Holy Spirit. When that happens, in His infinite mercy He brings a cloud over us. He gives us a sense of our folly and sin, and our conscience gives us no rest. The normal work of the Spirit is to show us the beauty of Christ and fill our hearts with Him. But if we grieve Him, He must turn our attention to ourselves and our sin. That lasts until we confess and He restores us.
Summary
- Source. One of two natures does the talking. Old self or new self — the words show which is in charge at that moment.
- Supply. Grace to give out comes from grace taken in. Time with the Lord feeds the mouth that builds others up.
- Standard. Not just clean words, but good ones — and good for this need, this hearer, this moment. Silence beats a word that meets no need.
- Scope. Wider than dirty talk. The same net catches useless and unwholesome speech. Words that fail to build are pulling down.
- Sequel. Careless speech grieves the Spirit. He must then turn us to our own sin instead of the beauty of Christ, until we confess.