Proverbs 18:4 The words of a man’s mouth are as deep waters, and the wellspring of wisdom as a flowing brook.
God promises that the words of a believer (a man who has in him the wellspring of wisdom) will be as refreshing as a flowing brook. Jesus says it this way: “Out of his heart (KJV, belly) will flow rivers of living water [John 7:38].” “This he said about the Spirit, whom those who believed in him were to receive [v. 39].” (The physical location of the spirit seems to be the belly, since this is a more precise translation of the Greek word, “koilos.”) The Spirit of God that resides in our spirit is a wellspring of wisdom. Words that come from there (from Him) are a flowing brook.
The truth of the promise is that the words that a believer speaks, when they come from the Spirit of God, are refreshing, encouraging, uplifting, and life-giving. But when the words come from the sinful flesh they, like deep waters, may be harmful and death-dealing. It is helpful for us to know that we are able to talk the words and wisdom of God from the Spirit; and when we do, it is pleasant like a flowing brook.
How do we do that? By hearing the gospel often enough to abide in the vine and to stay connected to God by faith. Then go about living and conversing, and trust that some of the things you say will bring a blessing.