What is the general rule regarding exceptions in sales?
Chapter on Selling Assets and Fruits
Al-Mughni
Book of Sales
Primary text
The principle governing exceptions is that what cannot be validly sold on its own, or what the remainder of the sold property cannot be validly sold on its own, cannot be validly excepted. This adheres to the school of thought of Abu Hanifa and Al-Shafi'i.
Supporting text
The companions of our school of thought made exceptions to this rule regarding the parts that fall off an animal ('sawaqit al-shāh') and its skin, due to reports indicating permissibility, specifically referencing the action of Ibn Umar. All other cases remain subject to the primary principle.