He was asked:

Regarding the hadith:

“He granted a concession allowing ‘arāyā sales on the basis of their estimated yield.”

What is meant by their estimated yield? And what of the hadith:

“He prohibited the sale of musarrāh and muhaffalah animals”?

He replied:

All praise is due to Allah. The terms “musarrāh and muhaffalah” refer to an animal—whether a camel, sheep, goat or another kind—that is left unmilked for several days so that milk accumulates in its udder. It is then sold, leading the buyer to think that it produces that much milk every day. This constitutes deception and fraud, which the Prophet, may Allah bless him and grant him peace, prohibited both generally and specifically. He granted the buyer a three-day option after milking it: if satisfied, he may keep it; if dissatisfied, he may return it, together with compensation for the milk present at the time of the sale. The Prophet, may Allah bless him and grant him peace, fixed this compensation at one sā‘ of dates.

As for sales involving uncertainty, where the seller cannot deliver the item—such as selling his runaway slave, his camel or horse that has strayed, or his bird that has escaped its cage or tether, and similar cases—selling such things falls under “risk-taking and gambling.” If the buyer manages to obtain the item, he has won the gamble against the seller, having acquired his property for less than its value; if he cannot obtain it, the seller has won the gamble against the buyer