Jawamiʿ al-hikayat wa lawamiʿ al-riwayat 23: Depreciation of Coin. [I. xii. 14.]

23

When Yaminu-d daula Mahmud came to the throne, and the effects of his greatness spread through all countries, and his rule swept away the idol temples and scattered the worshippers, some sharp men of India formed a plan (for enriching themselves). They brought out a dirham of great purity and placed a suitable price upon it. Time passed on and the coin obtained currency. Merchants coming from Muhammadan countries used to purchase these dirhams and carry them to Khurasan. When the people had grown accustomed to the value of the coin, the Indians began by degrees to debase the standard. The merchants were unaware of this depreciation, and finding a profit upon silver, they brought that metal and gold from all parts of the world, and sold it for (debased coins of) copper and brass, so that by this trick the wealth of the Muhammadans was drawn to Hindustan.
When 'Alau-d daula ascended the throne, this grievance had become intolerable, and he determined to remedy it, and consulted with the merchants as to the measures most proper to be taken to effect this purpose. They advised that the debased coinage should be exchanged for good from the royal treasury. Accordingly 'Alau-d daula gave the necessary orders, and 100,000,000 dirhams were issued from the treasury to the mint, and thence distributed to the servants of the Almighty as redress and compensation. The fame of this act spread the lustre of Alau-d daula's glory throughout the world.