ibn Abbas · The Book of Financial Transactions

" The Messenger of Allah ruled that what a slave earns belongs to his guarantor."

"Do not sell gold for gold except like for like and do not differentiate. Do not sell silver for silver except like for like, and do not sell it in return for something to be paid later."

he did not see anything wrong with it even if it was on credit.

This is what I have found on this topic.

"I came to the Prophet and said: 'Wait, I want to ask you something. I sell camels in Al-Baqi with a price set in Dinars but I accept Dirhams instead.' He said: 'There is nothing wrong with it if you take the price on that day, still unfinished business between you both (buyer and seller)"'

"When the Prophet (ﷺ) came to Al-Madinah, he called for a scale and weighed (something) for me and gave me more."

they used to buy and sell during the time of the Messenger of Allah at the top of the marketplace without measuring. The Messenger of Allah forbade them to sell it in the place where they had bought it until they moved it.

"The Messenger of Allah said: 'No man is bound by a transaction involving the sale of something that he does not possess.'''

"Any man who pollinates a date-palm tree then sells it, the fruits of the tree are for the one who pollinated it, unless the purchaser stipulated otherwise."

"We were traveling with the Messenger of Allah and I was riding a camel. The Messenger of Allah said to me: 'Will you sell it to me for such and such, may Allah forgive you?', I said, I said, 'Yes, it is yours, O Prophet of Allah.' He said: 'Will you sell it to me for such and such, may Allah forgive your?' I said: 'Yes, it is yours, O Prophet of "Allah.' He said: 'Will you sell it to…

the Messenger of Allah forbade selling loyalty or giving it away.

"The Messenger of Allah said: 'Allah, the Mighty and Sublime, admitted to paradise a man who was easygoing in buying and selling, in paying off debts and asking for repayment."' (Sahaih)