Muhammad bin Muslim bin Tadras محمد بن مسلم بن تدرس أبو الزبير · The Chapters on Business Transactions

"Let one of you not undersell another."

"I bear witness that the true and truly inspired one Abul-Qasim (ﷺ) told us: 'Selling a Muhaffalah is Khilabah, and Khilabah is not lawful for the Muslim."' (Ibn Majah said: " Meaning: 'Deception.")