But the things that proceed out of the mouth come out of the heart, and they defile the person. Bible

“come out of the heart.” The “heart” is the source of life. Mark 7:20-23 has a list of things that come out of the heart that is more inclusive that this list in Matthew. The Bible says in many different places that what comes out of the mouth generally originates in the heart (cp. Matt. 12:34; Luke 6:45). Although the biblical use of “heart” refers to the center of a person’s life and may include the interworking of the heart, brain, and other organs as well, modern medicine is now showing more and more each year that the actual physical heart not only has a leading role in directing the physical/chemical/emotional activities of the body, but has been shown to even have stored memories. Proverbs 4:23 tells us that above all else, we are to guard our heart, because from it come the issues of life. [For more on the heart, see commentary on Prov. 4:23].

Commentary for: Matthew 15:18