وذراع من ثوب وجذع في سقف وضربة القانص
Translation: Selling an unspecified cubit from a cloth, a beam still embedded in a roof, or whatever a hunter may catch on one attempt is not permitted.
The cases illustrate different problems. An unspecified cubit of cloth may be insufficiently identified. An embedded roof beam may cause harm if removed. A hunter's next catch may never materialize.
Separate the causes:
1. Lack of identification.
2. Inability to deliver without damage.
3. Selling an unpredictable future result.