ذِكْرُ الزَّجْرِ عَنْ بَيْعِ الْفِضَّةِ بِالْفِضَّةِ، وَالذَّهَبِ بِالذَّهَبِ، إِلَّا مِثْلًا بِمِثْلٍ
"The Messenger of Allah forbade selling silver for silver and gold for gold, unless it was of equal amounts. And he told us to sell gold for silver however we wanted, and silver for gold however we wanted. (Using translation from Nasāʾī 4578)
أَبُو بَكْرَةَ «نَهَى رَسُولُ اللَّهِ ﷺ أَنْ يَبْتَاعَ الْفِضَّةَ بِالْفِضَّةِ وَالذَّهَبَ بِالذَّهَبِ إِلَّا سَوَاءً بِسَوَاءٍ وَأَمَرَ أَنْ يَبْتَاعَ الْفِضَّةَ بِالذَّهَبِ كَيْفَ شَاءَ وَالذَّهَبَ بِالْفِضَّةِ كَيْفَ شَاءَ»