" الْبَيِّعَانِ بِالْخِيَارِ حَتَّى يَتَفَرَّقَا أَوْ يَأْخُذَ كُلُّ وَاحِدٍ مِنْهُمَا مِنَ الْبَيْعِ مَا هَوِيَ وَيَتَخَايَرَانِ ثَلاَثَ مَرَّاتٍ "
It was narrated from Al_Hasan, from Samurah, that the Prophet of Allah said: "Two trades have the choice as long as until they reach a deal that suits both of them and they confirm it three times. "