Ruling on buying books from Ibadiyyah sect

Question:

Is it permissible to do business with ibadiyyah? For example, I buy their good books and cassettes, should I stop or continue doing this?

Answer:

There is no harm in buying the useful books from anyone because of their great benefit. As for the books that contain heresy and error, it is not permissible to deal in them.

May Allah grant us success. May peace and blessings be upon our Prophet, his family and Companions