Habib reported that he heard Abu Minhal as saying: I asked al-Bara' bin Azib (RA) about the exchange of (gold for silver or vice versa), whereupon he said: you better ask Zaid bin Arqam for he knows more than I. So I asked Zaid but he said: You better ask al-Bara' for he knows more than I. Then both of them said: Allah's Messenger ( صلی اللہ علیہ وسلم ) forbade the sale of silver for gold when payment is to be made in future.