It is obligatory for a ‘muqallid’ (follower of a jurist) to learn the judgements about the problems which are faced by him usually. If a person does not know whether a thing is pure or not, he should refer to the relevant book or ask someone reliable to enlighten him. However, if in spite of knowing the legal position, he is doubtful whether or not the thing is pure — the thing is pure and it is not necessary for him to make investigation or inquiry about it.   _{Your Comment}