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.
أَنَّ النَّبِيَّ ﷺ قَالَ مَنِ اشْتَرَى شَاةً مُصَرَّاةً فَهُوَ بِالْخِيَارِ ثَلاَثَةَ أَيَّامٍ إِنْ شَاءَ رَدَّهَا وَصَاعًا مِنْ طَعَامٍ لاَ سَمْرَاءَ