´It was narrated that Ibn 'Umar said:` "We used to buy food from troops of riders (i.e., the caravans) without knowing the amount, but the Messenger of Allah (ﷺ) forbade us to sell it until it had been delivered to us."
Hadith ReferenceSunan Ibn Majah / The Chapters on Business Transactions / Hadith: 2229
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم