Selling gold for silver on credit is forbidden

I asked al-Bara b. Azib and Zayd b. Arqam ᴿᴬ about currency exchange. Each one of them would say, “This one is better than me,” and both of them said: The Messenger of Allah ﷺ forbade selling gold for silver on credit.

سَأَلْتُ الْبَرَاءَ بْنَ عَازِبٍ وَزَيْدَ بْنَ أَرْقَمَ ؓ عَنِ الصَّرْفِ، فَكُلُّ وَاحِدٍ مِنْهُمَا يَقُولُ: هَذَا خَيْرٌ مِنِّي، فَكِلاَهُمَا يَقُولُ: نَهَى رَسُولُ اللَّهِ ﷺ عَنْ بَيْعِ الذَّهَبِ بِالْوَرِقِ دَيْنًا.

that his father said, "The Prophet ﷺ forbade the selling of gold for gold and silver for silver except if they are equivalent in weight, and allowed us to sell gold for silver and vice versa as we wished."

نَهَى النَّبِيُّ ﷺ عَنِ الْفِضَّةِ بِالْفِضَّةِ وَالذَّهَبِ بِالذَّهَبِ إِلاَّ سَوَاءً بِسَوَاءٍ وَأَمَرَنَا أَنْ نَبْتَاعَ الذَّهَبَ بِالْفِضَّةِ كَيْفَ شِئْنَا وَالْفِضَّةَ بِالذَّهَبِ كَيْفَ شِئْنَا