´It was narrated from Malik, from Nafi from'Abdullah bin 'Umar that the Messenger of Allah said:` "The two parties to a transaction both have the choice so long as they both chosen to conclude the transaction." (Sahih )
Hadith ReferenceSunan an-Nasa'i / The Book of Financial Transactions / Hadith: 4470
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:متفق عليه