Abu Al-Jawza says that I heard a fatwa from Ibn Abbas (may Allah be pleased with him) regarding the transaction of buying and selling gold and silver, and for a long time I kept giving people that same fatwa. When I met him again, he had retracted his fatwa. I asked him the reason for this, and he said that it was only my opinion which I had formed, but later Abu Saeed Al-Khudri (may Allah be pleased with him) informed me that the Prophet (peace and blessings be upon him) had prohibited this.