Oh people! Indeed many of the common people give fatawa to one another without any knowledge. So you find them saying “this is halal, or this is haraam, or this is waajib” etc And he knows (nothing) about these affairs. Does this man not know that Allah will ask him about what he said on the Day of Resurrection?!

Does he not know that if he misguided an individual – that if he made permissible that which Allah has made haraam or made haraam that which Allah has made halal for the person – then he is the cause for that persons sins.

And does he not know that he will have the like of those sins for those actions which were caused by his fataawa?!

Slightly paraphrased

خطبة الشيخ العثيمين: تحريم الإفتاء بغير علم