As far as we know, the Prophet (peace be upon him) is not authentically reported to have said: "Pay Zakah according to the (Part No. 9; Page No. 319) estimated price of today." However, scholars who hold the view that
Zakah is due on commercial commodities like gold and silver or banknotes, consider that these commodities are mainly used for trading purposes which bring higher profits. That is why Zakah becomes due on their estimated value when it reaches the prescribed Nisab (the minimum amount on which Zakah is due) and a full lunar year has elapsed. A Hadith is narrated in this respect
on the authority of
Abu Dawud (may Allah be merciful to him)
Samurah Ibn Jundub (may Allah be pleased with him) who said:
The Messenger of Allah (peace be upon him) ordered us to pay the sadaqah (Zakah) on what we prepared for trade.
Another Hadith narrated to the same effect on the authority of
Abu Dhar (may Allah be pleased with him) also supports the above Hadith.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.