The Messenger of Allah ﷺ forbade the sale of urban (a non-refundable deposit). Malik said, "What this means, in our view, and Allah knows best, is that a man buys a slave or hires an animal, then says, 'I will give you a dinar on the condition that if I cancel the sale or the hire, what I gave you is yours.'"
حدثنا عبد الله بن مسلمة قال قرأت على مالك بن أنس أنه بلغه
نهى رسول الله ﷺ عن بيع العربان قال مالك وذلك فيما نرى والله أعلم أن يشتري الرجل العبد أو يتكارى الدابة ثم يقول أعطيك دينارا على أني إن تركت السلعة أو الكراء فما أعطيتك لك
No references are available.
[Hasan] Reported by Ibn Majah, Trade Transactions, Chapter on the Sale by Deposit (Urban), no. 2192, from the hadith of Malik with this chain. The one who relayed it in full was Ibn Lahia (Tamhid 24/177), and he stated explicitly that he heard it directly, and Harith bin Abdul-Rahman bin Abu Dhubab followed him in narrating it, as found in Bayhaqi 5/343, and its chain is hasan. It also appears in the Muwatta (Yahya's recension) 2/609, Tamhid 24/176, Istidhkar no. 1251, and Zurqani no. 1331, where Malik narrates from the trustworthy source he relied on, from Amr bin Shuayb, and so on.