Smak bin Hrb bin Aws سماك بن حرب بن أوس · The Book of Financial Transactions

Muawiyah sold a cup of gold or silver for more than its weight. Abu Ad-Darda' said: "I heard the Messenger of Allah forbid such transactions unless it was like for like."

"On the Day of Khaibar I bought a necklace containing gold and ggems for twelve Dinars. The I took it apart and found that it contatined more than twelve Dinars. Mentiion of that was made to the Prophet and he said: 'It should not be sold until it is taken apart."

"The Messenger of Allah forbade us from selling silver for silver unless it was of equal amounts, or selling gold for gold unless it was of equal amounts. The messenger of Allah said: 'Sell gold for silver however you want, and silver for gold however you want."'

"I used to sell camels at Al-Baqi and I would sell Dinars in exchange for Dirhams. I came to the Prophet in the house of Hafsah and said: 'O Messenger of Allah, I want to ask you: I sell camels in Al-Baqi and I sell Dinars in exchange for Dirhams. He said: 'There is nothing wrong with it if you take the price on that day, unless you depart when there is still unfinished business between you both (buyer and…

"I used to sell gold for silver, or silver for gold. I came to the Messenger of Allah and told him about that, and he said: 'If you make a deal with your companion, d o not leave him when there is still any ambiguity (in the deal) between you."'