https://torontodawah.com/the-ruling-on-performing-a-transactions-called-as-salaam-making-an-advance-payment-for-something-which-isnt-available-at-the-time-of-purchase-and-the-details-concerning-urbun-down-payment-sale/
The Ruling On Performing A Transactions Called As-Salaam (Making An Advance Payment For Something Which Isn't Available At The Time Of Purchase) And The Details Concerning 'Urbun (Down Payment Sale) - Shaykh Abdul-Muhsin Al-Abbaad, Lajnah (Permanent Committee For Scholarly Research And Ifta’) And Shaykh Ibn Uthaymeen