From the Good Manners of Correcting Mistakes
Concerning the position, ‘I don't speak about anyone and I don't want anyone speaking about me.’ This position is made with good intentions and in shāʾ Allāh is intended to avoid fitnah. However, is this statement correct or should we be open to giving and receiving advice, commanding the good, forbidding the evil, saying that which is for us and that which is against us?
If he is from ahl al-sunnah, no one is free from errors, so you advise him with good and kind advice, if his mistake has spread then refute his mistake but do not refute him.
Shaykh ʿAbdullāh al-Bukhārī