Sahih Bukhari | Volume 3 | Hadith Number 353

Narrated by 'Abdullah bin 'Umar
Allah's Apostle forbade the sale called 'Habal-al-Habala which was a kind of sale practiced in the Pre-Islamic Period of ignorance. One would pay the price of a she-camel which was not born yet would be born by the immediate offspring of an extant she-camel.