Proverbs 30:5
"Every word of God is pure: he is a shield unto them that put their trust in him."
Your word is your character. There used to be a day in America when if a man said something it was good. If a man said he was going to do something and they shook hands, then that would be as good as a contract. Now, people sign contracts and then hire an attorney to get them out of the contract. A person's word is no longer something upon which you can depend.
God is still a God of His Word. Though times have changed, God's Word is still pure. God says in the verse above, "Every word of God is pure..." The word "pure" means without any falsehood. When God gave us His Word, He made sure that everything He said could be depended upon.
God goes further to show us the purity of His Word when He says, "The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times." (Psalm 12:6) God said, just like silver is put into the furnace to be purified, He also purified His Word seven times to be sure of It's veracity.
Let me illustrate by using an authors writings, though this is a poor illustration to compare to God's Word. When I write a book, I send it to my proofer, and she goes through it and checks it grammatically, for spelling errors and for readability. Every once in awhile she will show me something that may not seem to agree. What she is doing is purifying my words. She is checking them to make sure everything is correct.
God proofed or purified His Word by making sure everything He said is correct. He made sure there was no falsehood in It. He made sure there was not deception in His promises. He made sure there was no flattery in His way. He made sure that everything He said was absolutely true. God wanted His Word to be pure, and a Word upon which we can depend.
If God felt it was that important to have a pure Word, then you should be sure that what you say is correct. Be sure there is no falsehood in what you say before you say it. In other words, don't say something that you know is not true. Be honest in all that you say.
Moreover, be measured in all that you say. In other words, don't flippantly say something that you have not thought about. Too many times we say we are going to do something without thinking about it, then we go back on our word. When you can't stand by your word, then your word means nothing. This is why you need to be slow to answer and be measured with what you say.
Furthermore, your words should be words that are not deceptive. In other words, don't say something in code that you know can be taken one way, but you meant it another. Be clear with what you say. Don't be a person whom people cannot trust because every word must be parsed. When you say something, mean it.
Your words should be as pure as God's. You are Christ's representative, and what you say will either validate God's Word or put doubt upon it. Be sure what you say is true so as to not bring any mark upon the Word of God. Yes, God's Word always stands pure, but the world will measure it by what you say. Be sure your words are always true.