Sahih Bukhari Volume 003, Book 035, Hadith Number 457.
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 'Abdullah : The people used to sell camels on the basis of Habal-al-Habala. The Prophet forbade such sale. Nafi' explained Habalal-Habala by saying. "The camel is to be delivered to the buyer after the she-camel gives birth."