The Prophet ﷺ as saying: If anyone buys sheep whose udders have been tied up, he has option for three days: he may return it if he desires with a sa' of any grain, not (necessarily) wheat. (Using translation from Abū Dāʾūd 3444)

عَنِ النَّبِيِّ ﷺ قَالَ مَنِ اشْتَرَى شَاةً مُصَرَّاةً فَهُوَ بِالْخِيَارِ إِنْ شَاءَ رَدَّهَا وَصَاعًا مِنْ تَمْرٍ