Summary: The little fox of sinful speech traps many believers and ruins their witness.
Song of Solomon 2:15 KJV Take us the foxes, the little foxes, that spoil the vines: for our vines have tender grapes.
Ephesians 4:29 KJV Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers.
Ephesians 4:29 ESV 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.
Ephesians 4:29 MSG Watch the way you talk. Let nothing foul or dirty come out of your mouth. Say only what helps, each word a gift.
Ephesians 4:29 NASB Let no unwholesome word proceed from your mouth, but only such a word as is good for edification according to the need of the moment, so that it will give grace to those who hear.
Ephesians 4:29 Moffatt NT Let no bad word pass your lips, but only such speech as is good for edification, as occasion may require, words that are gracious and a means of grace to those who hear them.
Ephesians 4:29 J B Phillips Let there be no more foul language, but good words instead—words suitable for the occasion, which God can use to help other people.
Ephesians 4:29 NLT Don’t use foul or abusive language. Let everything you say be good and helpful, so that your words will be an encouragement to those who hear them.
I. INTRODUCTION—SINFUL SPEECH
Thomas Manton—The tongue had need to be restrained with force and watchfulness, for it is quick and ready to bring forth every wicked conception. You must not only watch over it, but bridle it; it is good to break the force of these constraints within us, and to suffocate and choke them in the first conception.
Bishop Stevens—You can sooner make the condor of the Andes perch upon your wrist; you can sooner make leviathan sport with you in the cresting surf; you can sooner make the boa-constrictor coil harmlessly around your neck; you can sooner make the lion so gentle that a little child can lead him , the tame the tongue; for the “tongue can no man tame.”
A. Biblical References to Sinful Speech in Proverbs
The Bible is full of exhortations and admonitions concerning the tongue. In the book of Proverbs there are around sixty warnings and instructions of various kinds concerning the tongue. We find in Proverbs some of the following descriptions of the tongue and words in general:
• A lying tongue—Proverbs 6:17; 12:19; 21:6; 26:28
• A tongue of flattery—Proverbs 6:24; 28:23
• The tongue of the just—Proverbs 10:20
• A froward (disobedient; opposing) tongue—Proverbs 10:31
• The tongue of the wise—Proverbs 12:18; 15:2
• A wholesome tongue—Proverbs 15:4
• A naughty tongue—Proverbs 17:4
• A perverse tongue—Proverbs 17:20
• The tongue is powerful—Proverbs 18:21
• A kept tongue—Proverbs 21:23
• A soft tongue—Proverbs 25:15
• A backbiting (mean; spiteful) tongue—Proverbs 25:23
• A kind tongue—Proverbs 31:26
• There is deceptive speech—Proverbs 7:21
• There is excellent speech—Proverbs 17:7
• Words of understanding—Proverbs 1:2
• Words of the wise—Proverbs 1:2; 22:17
• Flattering words—Proverbs 2:16
• Words that snare—Proverbs 6:2
• Righteous words—Proverbs 8:8
• Grievous words—Proverbs 15:1
• Pure and pleasant words—Proverbs 15:26; 16:24
• Words of a talebearer—Proverbs 18:8; 26:22
• Words of knowledge—Proverbs 19:27; 23:12
• Words of truth—Proverbs 22:21
• Hasty words—Proverbs 29:20
From these few references we can see how important the tongue and the patterns of our speech are.
B. Jesus and the Impact of Careless Words
Matthew 12:36-37 KJV But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.  For by thy words thou shalt be justified, and by thy words thou shalt be condemned.
Passages like this are good at assisting us in our walk in holiness. Passages like this should trouble us to the extent that we are willing to let the Holy Ghost guide and direct us in correct direction of life. We are going to be accountable for the words that we speak and there will be a great accounting at the day of judgment.
Idle words are those words that come from pride and deceit. The proud words are those which are perceived as boastings of a vain fellow. The deceitful words are those cunning words that work toward deceiving someone so that an ill-gotten gain may be enjoyed. Idle words can be those words that are heard as they report various kinds of misinformation that maims the reputation of another person. Idle words are those words of an idle mind and come forth as impure and polluted with lust. Idle words can be useless and insignificant themes of a mindless nature. The reality of the matter is that our words are a very clear reflection of our heart.