Matthew Henry Commentary Ezekiel 33:30-33

"And as for thee, son of man, the children of thy people talk of thee by the walls and in the doors of the houses, and speak one to another, every one to his brother, saying, Come, I pray you, and hear what is the word that cometh forth from Jehovah. And they come unto thee as the people cometh, and they sit before thee as my people, and they hear thy words, but do them not; for with their mouth they show much love, but their heart goeth after their gain. And, lo, thou art unto them as a very lovely song of one that hath a pleasant voice, and can play well on an instrument; for they hear thy words, but they do them not. And when this cometh to pass, (behold, it cometh,) then shall they know that a prophet hath been among them." — Ezekiel 33:30-33 (ASV)

Unworthy and corrupt motives often lead people to the places where the word of God is faithfully preached. Many come to find something to oppose: far more come out of curiosity or mere habit. People may have their hearts changed. But whether people hear or refrain, they will know by the outcome that a servant of God has been among them. All who will not know the worth of mercies by making good use of them, will justly be made to know their worth by the lack of them.