It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said: "Whoever attributes to me something which I have not said, let him take his place in the Fire," "and whoever is consulted by his Muslim brother and gives him wrong advice, he has betrayed the one who consulted him," "and whoever gives a wrong fatwa without knowledge (and the one who asked acts upon it), then its sin will be upon the one who gave the fatwa."
Hadith Referenceالادب المفرد / كتاب المشورة / 259
Hadith Gradingالألبانی:صحيح
Hadith Takhrij«صحيح : الحديث الأول فى ابن ماجه ، المقدمة ، باب التغليظ فى تعمد الكذب على رسول الله صلى الله عليه وسلم : 34 و الثالث فى ابن ماجة ، المقدمة : 53 و أحمد : 8266 و اسحاق بن راهويه فى مسنده : 340/1 و الحاكم : 126/1 و رواه أبوداؤد مختصرًا : 3657»