"Two trades have the choice as long as until they reach a deal that suits both of them and they confirm it three times. " (Using translation from Nasāʾī 4481)
«الْبَيِّعَانِ بِالْخِيَارِ حَتَّى يَتَفَرَّقَا أَوْ يَأْخُذَ كُلُّ وَاحِدٍ مِنْهُمَا مِنَ الْبَيْعِ مَا هَوِيَ وَيَتَخَايَرَانِ ثَلَاثَ مِرَارٍ»