Al-Allaamah Rabee bin Haadi Al-Madkhali (may Allaah preserve him) stated:
If a scholar-a criticizer- disparages a person who is deserving of disparagement and warns against him due to his bidah, then this (scholar) is from the people of justice and (from) those who are sincere to the religion of Islaam and the Muslims, and he is not an oppressor; rather he is a person who has fulfilled an obligation. If he keeps quiet about someone who deserves to be disparaged and warned against, then he is one who betrays and deceives Allaah’s religion and the Muslims. If he goes very far in his silence (i.e. not speaking the truth), such that he defends and shelters bidah and its people, then indeed he has destroyed himself, dragged those who listen to him into a debacle and make them assiduous in aiding falsehood and rejecting truth.
[Source: Al-Mahajjah Al-Baydaa Fee Himaayah As-Sunnah Al-Gharraa Min Zallaat Ahl Al-Akhtaa Wa- Zaighi Ahl Al-Ahwaa’ page: 31]
Abu Mu’aawiyah (Abdullah Al-Gambi)