Buying and Selling: Annulling a Transaction Without the Seller's Consent
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 2143
If at any time after buying a commodity a person realises that it has a defect, he can annul the transaction even if the seller is not prepared to accept it. The same rule applies to the other options for annulling a transaction.
-Ayatullah Sistani, Practical Laws of Islam, Buying and Selling