Ma'tmar bin Sulaiman-al-Taufayl معتمر بن سليمان - الطفيل · The Book of Financial Transactions

the Messenger of Allah forbade meeting traders on the way.

"No tow-dweller should sell for desert-dweller, no man should outbid his brother; and no woman should ask for her sister (in faith) to be divorced so as to turn over what is in her bowl (deprive her of her share of maintenance)"

"The Messenger of Allah forbade lending on the condition of a sale, selling what you do not have, and profiting on what you do not possess.