Now, there is nothing really wrong with such a statement, as we know that the Word of God usually does have some effect, whether good or bad, on whomever hears it. It is the basis and Scriptural support for such a statement that is erroneously used in most cases. It has been said and passed on, and repeated so often, that most people these days do not even know the reference, or what is actually said. The reference comes from Isaiah 55:11, but just a simple cursory reading is almost enough to clear up the misuse, but putting it back into the context even more so:
For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD. For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts. For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater: So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it.So the thrust of what is being said here is that when the Lord says something, when he sends forth his word, when he sets forths his word to do something, it will be done and will in no way be thwarted or return unto him void.
So while we can stand firm on a belief that the Word of God is indeed powerful, using this verse as some kind of blanket assurance or defense that no matter how we put God's Word out there, it will work, as is commonly done, is to offer false assurance and is a mishandling of Scripture.
I did not have to look far after a quick Google search on this phrase, to find posts that misused it. As expected, one such post used it as a blanket statement for all of Scripture, and especially the words of Christ, in saying:
This verse along with many others in the bible explain the fact that Jesus power is everywhere. He does not have to be present for you to receive His Gift. His Grace and His word is sufficient to deliver all that you need. In other words if Jesus said it, then it is so and whatever you ask in his name, so shall you have. Once the word of the Lord is sent out, it will not return void.It just pays to stop and examine any such "pet" verses we may find always on the tip of our tongue. Take a quick look at the context of the Scripture, to make sure we are not using things out of context to say something we want, rather than what it is actually saying.
This is a spiritual truth that many believers have used over the years, by memorizing and saying the words of Jesus, many have been healed of afflictions, many have overcome some of the most dire circumstances imaginable...
You must release the power of Jesus within you and through you when confronting the dangers of this satan filled world. His word as given to us in the Bible will never, ever return void and unfulfilled. You can bank on that revelation for eternity.