Amr bin Shu'ayb narrates from his father, from his grandfather (Sayyiduna Abdullah bin Amr, may Allah be pleased with them both), that the Prophet (peace and blessings be upon him) "forbade a loan combined with a sale, forbade two deals in one sale, and forbade taking profit on goods for whose loss responsibility has not been assumed."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10922