How to Deny Evil with the Heart

Question:
What do we mean by denying evil with the heart?

Answer:
Denying evil with the hand is well known: erasing an image, spilling out intoxicants, separating people who have gathered for falsehood, and the like. Denying it with the tongue is also well known: saying, "This is permissible," "This is an abomination," or "This is not lawful for you, so-and-so!"
As for the heart, one must detest it in his heart, his face must change, and he must dislike the matter in his heart. Allah knows from his heart that he disliked this thing and denied it; he does not agree with it or approve of it. Even if he denies it with his tongue, if he denies it with his heart, he should stand up and not witness it; he should leave and not witness the abomination.

Question: He should not witness it. For example, a man who uses singing and is addicted to using singing. Whenever you advise him verbally, meaning you continue with him, eventually he says, "O son of the noble, you have become too much for us. Why do you keep advising us about this talk? We have put on our adornment, but as for this, it is what you and your like say." How does he deny it? Does he sit with him, or does he leave him and sit in his house??

Answer: Boycott them. This is an abomination. You have now denied it with your tongue, but do not sit with them.