Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: Whoever says something that is not in the Book of Allah, nor from the sayings of the Messenger, and says it from his own opinion, then he does not know how much he will have to bear its consequences when he meets Allah, the Mighty and Majestic.
Hadith Referenceسنن دارمي / مقدمه / 160
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده صحيح إذا كان عبدة سمعه من ابن عباس، [مكتبه الشامله نمبر: 160]
Hadith Takhrijیہ سیدنا ابن عباس رضی اللہ عنہما کا قول ہے جس کی سند صحیح ہے۔ دیکھئے: [البدع 94] ، [الأحكام 782/6] ، [المدخل 190] ، [الفقيه 183/1]
Brief Explanation
(Commentary on Hadiths 158 to 160)
Issuing a fatwa (legal verdict) without referring to the Qur’an and Hadith and without any evidence is tantamount to declaring the unlawful (haram) as lawful (halal) and the lawful as unlawful.