What is the ruling on greeting a person who is engaged in a sin?

The Shaykh : He says: What is the ruling on greeting someone who is engaged in a sin, such as smoking? Do you greet him and advise him? Yes. Not just one, but a group of people. You greet them. Huh? No, I seek refuge in Allah. I did not sit with them, I greeted them, I was angry with them, so I greeted them. No, I am not mistaken. Is he not a believer? Well, did not the Messenger (peace and blessings be upon him) forbid boycotting one’s Muslim brother for more than three days? This is not causing confusion, Muhammad al-Sayyid. Yes.