Hadith 513660
Chapter 31: Business Transactions - كتاب البيوع
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " الْمُتَبَايِعَانِ كُلُّ وَاحِدٍ مِنْهُمَا بِالْخِيَارِ عَلَى صَاحِبِهِ مَا لَمْ يَتَفَرَّقَا إِلاَّ بَيْعَ الْخِيَارِ " .
Yahya related to me from Malik from Nafi from Abdullah ibn Umar that the Messenger of Allah, may Allah bless him and grant him peace, said, "Both parties in a business transaction have the right of withdrawal as long as they have not separated, except in the transaction called khiyar." Malik said, "There is no specified limit nor any matter which is applied in this case according to us."
Reference Muwatta Malik 513660
USC-MSA web (English) reference : Book 31, Hadith 80