`Allâmah Zayd bin Muhammad al-Madkhalee (died 1435)
Question: Is it permissible to slander Ahl-ul-Bid`a and describe them in a way that entails slander in connection with warning against them?
Answer: There is no need for cursing them. It solves no problems. However, their mistakes must be clarified. Clarifications and warnings against their innovations must be scientific so that people do not fall into them and thus be ruined. One should not slander them or insult them, but clarify their mistakes and transgressions.
Innovations vary. There are major innovations whose practitioners are bad-mouthed and warned against. Other innovations do not reach that level. In such cases, the innovator’s errors must be clarified, and if he calls to his innovation – he should also be warned against.