وَإِذَا اشْتَرَى بِهَا سِلْعَةً ثُمَّ كَسَدَتْ وَتَرَكَ النَّاسُ الْمُعَامَلَةَ بِهَا بَطَلَ الْبَيْعُ عِنْدَ أَبِي حَنِيفَةَ
Translation: If goods were bought with these coins, then the coins fell out of circulation and people stopped dealing in them, the sale fails according to Abu Hanifah.
The case especially concerns a price still outstanding when the stipulated means of payment loses currency status. It does not simply declare every already-completed sale retrospectively void.
Opening interactive controls...
Coins become obsolete after the sale
Bab al-Sarf: Mixed Currency Exchanges, Debased Coins and Obsolescence
وَإِذَا اشْتَرَى بِهَا سِلْعَةً ثُمَّ كَسَدَتْ وَتَرَكَ النَّاسُ الْمُعَامَلَةَ بِهَا بَطَلَ الْبَيْعُ عِنْدَ أَبِي حَنِيفَةَ
Translation: If goods were bought with these coins, then the coins fell out of circulation and people stopped dealing in them, the sale fails according to Abu Hanifah.
The case especially concerns a price still outstanding when the stipulated means of payment loses currency status. It does not simply declare every already-completed sale retrospectively void.