The Prophet ﷺ said: If anyone buys a sheep whose udders have been tied up, he has option for three days (for decision). If he returns it, he should return with it wheat equal to its milk or double of it.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنِ ابْتَاعَ مُحَفَّلَةً فَهُوَ بِالْخِيَارِ ثَلاَثَةَ أَيَّامٍ فَإِنْ رَدَّهَا رَدَّ مَعَهَا مِثْلَ أَوْ مِثْلَىْ لَبَنِهَا قَمْحًا  

"The Messenger of Allah ﷺ said: 'Whoever buys a Muhaffalah, (1) he has the choice (of annulling the deal) for three days. If he returns it, then he must also give wheat equal to twice, the amount of its milk, or equal to the amount of its milk."'  

قَالَ رَسُولُ اللَّهِ ﷺ يَا أَيُّهَا النَّاسُ مَنْ بَاعَ مُحَفَّلَةً فَهُوَ بِالْخِيَارِ ثَلاَثَةَ أَيَّامٍ فَإِنْ رَدَّهَا رَدَّ مَعَهَا مِثْلَىْ لَبَنِهَا أَوْ قَالَ مِثْلَ لَبَنِهَا قَمْحًا  

[Machine] I heard Abdullah bin Umar say, "We used to wait for the Messenger of Allah ﷺ at the gate, and when he came out, we would follow him until he reached a hill outside the city. He sat down on it and said, 'O people, no one among you should undertake a transaction (buying or selling) until the migrants have an opportunity to do so with the Bedouins. And whoever sells a piece of land, he has the right to take it back within three days, and if he wants to return it, he should return it with an additional payment of similar value or he can return it as it is. The price of its milk and wheat should be fair.' All of Ibn Umar's sons acquired individual ownership of land through this narration." Al-Bukhari commented on this narration, "It is a subject of scrutiny."  

سَمِعْتُ عَبْدَ اللهِ بْنَ عُمَرَ يَقُولُ كُنَّا عَلَى بَابِ رَسُولِ اللهِ ﷺ نَنْتَظِرُهُ فَخَرَجَ فَاتَّبَعْنَاهُ حَتَّى أَتَى عَقَبَةً مِنْ عِقَابِ الْمَدِينَةِ فَقَعَدَ عَلَيْهَا فَقَالَ يَا أَيُّهَا النَّاسُ لَا يَتَلَقَّيَنَّ أَحَدٌ مِنْكُمْ سُوقًا وَلَا يَبِيعَنَّ مُهَاجِرِيٌّ لِأَعْرَابِيٍّ وَمَنْ بَاعَ مُحَفَّلَةً فَهُوَ بِالْخِيَارِ ثَلَاثَةَ أَيَّامٍ فَإِنْ رَدَّهَا رَدَّ مَعَهَا مِثْلَ أَوْ قَالَ مِثْلَيْ لَبَنِهَا قَمْحًا تَفَرَّدَ بِهِ جُمَيْعُ بْنُ عُمَيْرٍ قَالَ الْبُخَارِيُّ فِيهِ نَظَرٌ  

"مَنْ ابْتَاعَ مُحَفَّلةً فَهُوَ بِالخِيارِ ثَلاثَةَ أَيَّام، فَإِنْ رَدَّهَا رَدَّ معَهَا مِثْلَ لَبَنِهَا قمْحًا".