[Machine] The Messenger of Allah ﷺ prohibited selling gold for paper currency, considering it sinful. He informed us that this is, indeed, usury.
إِنَّ رَسُولَ اللهِ ﷺ نَهَى عَنْ بَيْعِ الذَّهَبِ بِالْوَرِقِ نَسِيئَةً وَأَخْبَرَنَا أَوْ قَالَ إِنَّ ذَلِكَ هُوَ الرِّبَا