The world (falsely) teaches that a “bad mouth” can belong to a “good heart” but “not” according to Lord Jesus Christ.

Our Blessed Lord implies that to “know” one’s “heart”, you got to “listen” to the “words” spoken by his mouth as this verse reveals:

“A good man brings good things out of the good stored up in his heart, and an evil man brings evil things out of the evil stored up in his heart. For the mouth speaks what the heart is full of.” – Lord Jesus Christ (Luke 6:45)

P/S:

If the “words” are “bad”,

“But the things that proceed out of the mouth come from the heart, and those defile the man.” – Lord Jesus Christ (Matthew 15:18)

He asks:

“O generation of vipers (snakes), how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh.” – Lord Jesus Christ (Matthew 12:34)

Now, that’s “how” we may “listen to the heart”.

But if there’s a “change” of “heart”, likewise, the “words” will “change” accordingly.