وإذا قبض المشتري المبيع في البيع الفاسد بأمر البائع وفي العقد عوضان كل واحد منهما مال ملك المبيع ولزمته قيمته ولكل واحد من المتعاقدين فسخه فإن باعه المشتري نفذ بيعه
Translation: In a defective sale of recognized property, authorized possession can confer ownership with liability for the item’s value; each party may rescind, and an onward sale by the buyer can take effect.
Four elements matter:
1. The sale is technically fasid, not simply batil.
2. Both countervalues are legally recognized property.
3. Possession occurs with the seller’s authorization.
4. The parties retain a legal basis to unwind the defective transaction.
A machine transferred under an invalid added condition may acquire restricted legal consequences after authorized possession. That does not retroactively make the condition lawful.