(9) باب ذِكْرِ الاِخْتِلاَفِ عَلَى نَافِعٍ فِي لَفْظِ حَدِيثِهِ
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 )
Reference: Sunan an-Nasa'i 4465
In-book reference: Book 44, Hadith 17
English translation: Vol. 5, Book 44, Hadith 4470