Sahih Bukhari Volume 003, Book 035, Hadith Number 448.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 35. Sales in Which a Price is paid for Goods to be Delivered later (As-Salam)
Narated By Muhammad bin Abi Al-Mujalid : As above (446) and said, "We used to pay them in advance for wheat and barley (to be delivered later). Narrated Ash-Shaibani... "And also for oil."