Messenger of Allah ﷺ 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.  

أَنَّ رَسُولَ اللَّهِ ﷺ نَهَى عَنْ بَيْعِ حَبَلِ الْحَبَلَةِ وَكَانَ بَيْعًا يَتَبَايَعُهُ أَهْلُ الْجَاهِلِيَّةِ كَانَ الرَّجُلُ يَبْتَاعُ الْجَزُورَ إِلَى أَنْ تُنْتَجَ النَّاقَةُ ثُمَّ تُنْتَجُ الَّتِي فِي بَطْنِهَا