From Ephesians 4 and the beginning of 5:

Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity. But that is not the way you learned Christ!— assuming that you have heard about him and were taught in him, as the truth is in Jesus, to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.

Therefore, having put away falsehood, let each one of you speak the truth with his neighbor, for we are members one of another. Be angry and do not sin; do not let the sun go down on your anger, and give no opportunity to the devil. Let the thief no longer steal, but rather let him labor, doing honest work with his own hands, so that he may have something to share with anyone in need. Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear. And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption. Let all bitterness and wrath and anger and clamor and slander be put away from you, along with all malice. Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you. Therefore be imitators of God, as beloved children. And walk in love, as Christ loved us and gave himself up for us, a fragrant offering and sacrifice to God.

One of the few things I’ve said from the pulpit that was obviously remembered (the person brought it up to other people months later) was the fact that Paul does not want us speaking all the truth we know to other people. On the contrary, telling the truth can be as much a violation of another person as a falsehood. Paul deliberately introduces the topic by making an analogy with a thief.

Let the thief no longer steal, but rather let him labor, doing honest work with his own hands, so that he may have something to share with anyone in need.

Stop taking and start working and saving so that you can begin giving. Has Paul lost his train of thought? Is he violently changing the subject? Not at all. Having established the principle in one place he now uses it in another:

Let no corrupting talk come out of your mouths, but only such as is good for building up, as fits the occasion, that it may give grace to those who hear.

So the alternative to “corrupting talk” is only what is good to build up a hearer at that time.

What bothers me about this, and the reason I bring it up now, is that I had to learn if from Ephesians. Because this teaching is repeated over and over again in Proverbs. Not only that, but reading Proverbs forces you to consider the economics as an analogy for speech ethics. Consider how the second book in Proverbs (which begins in chapter 10) so quickly morphs from issues of working v. robbing to speech:

The proverbs of Solomon. A wise son makes a glad father,
but a foolish son is a sorrow to his mother.
Treasures gained by wickedness do not profit,
but righteousness delivers from death.
The Lord does not let the righteous go hungry,
but he thwarts the craving of the wicked.
A slack hand causes poverty,
but the hand of the diligent makes rich.
He who gathers in summer is a prudent son,
but he who sleeps in harvest is a son who brings shame.
Blessings are on the head of the righteous,
but the mouth of the wicked conceals violence.
The memory of the righteous is a blessing,
but the name of the wicked will rot.
The wise of heart will receive commandments,
but a babbling fool will come to ruin.
Whoever walks in integrity walks securely,
but he who makes his ways crooked will be found out.
Whoever winks the eye causes trouble,
but a babbling fool will come to ruin.
The mouth of the righteous is a fountain of life,
but the mouth of the wicked conceals violence.
Hatred stirs up strife,
but love covers all offenses.
On the lips of him who has understanding, wisdom is found,
but a rod is for the back of him who lacks sense.
The wise lay up knowledge,
but the mouth of a fool brings ruin near.
A rich man’s wealth is his strong city;
the poverty of the poor is their ruin.
The wage of the righteous leads to life,
the gain of the wicked to sin.
Whoever heeds instruction is on the path to life,
but he who rejects reproof leads others astray.
The one who conceals hatred has lying lips,
and whoever utters slander is a fool.
When words are many, transgression is not lacking,
but whoever restrains his lips is prudent.
The tongue of the righteous is choice silver;
the heart of the wicked is of little worth.
The lips of the righteous feed many,
but fools die for lack of sense.