Is it permissible to be harsh with those who worship graves and call out, “O so-and-so, O so-and-so,” or should we advise them gently and call them to the truth gently?

Question:
Honorable Shaykh, may Allah grant you success, is it permissible to be harsh with those who worship graves and call out, “O so-and-so, O so-and-so,” or should we advise them gently and call them to the truth gently?

Answer:
One who accepts advice should be advised with gentleness and compassion, but as for the one who does not accept advice, he should be dealt with harshly. Be harsh with them if they do not accept it; there is nothing for them but harshness. Gentleness is for the one who accepts.