Is it valid if an agent, authorized to sell a slave for a fixed price of one hundred, sells a portion of the slave for less than one hundred?
General Chapter
Al-Mughni
Book of Agency
Primary text
If the agent is specifically authorized to sell the slave for one hundred and sells a part of it for less than that sum, the sale is invalid. This invalidity rests on the fact that the principal did not authorize the partial sale, nor did custom imply permission for such a transaction. Therefore, harm results to the principal due to the division, which was not explicitly or customarily permitted, similar to purchasing only half of a slave when authorized to purchase the whole.
Supporting text
Abu Hanifa permits this when the agency was general (absolute), based on his principle that an agent with absolute authority can sell for whatever price they desire. However, Al-Shafi'i, Abu Yusuf, and Muhammad rule it invalid, holding that the principal's consent for the whole price was not implicitly extended to a lesser price for a portion.