حَدَّثَنَا إِسْحَاقُ بْنُ عِيسَى، حَدَّثَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ
رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ الْمُتَبَايِعَانِ بِالْخِيَارِ مَا لَمْ يَتَفَرَّقَا أَوْ يَكُونُ الْبَيْعُ خِيَارًا
The Messenger of Allah (sallallahu alayhi wa sallam) said: “The two parties to a transaction have the option (of cancelling it) so long as they have not parted or there is a condition which gives the option to cancel.”.
Musnad Ahmad 371, Book 3, The Hadeeth of Saqeefah, Hadith 3. 1 min read