Sahih Bukhari Volume 3, Book 34, Hadith 2117

قَالَ أَبُو عَبْدِ اللَّهِ وَقَالَ اللَّيْثُ حَدَّثَنِي عَبْدُ الرَّحْمَنِ بْنُ خَالِدٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ ـ رضى الله عنهما ـ قَالَ بِعْتُ مِنْ أَمِيرِ الْمُؤْمِنِينَ عُثْمَانَ مَالاً بِالْوَادِي بِمَالٍ لَهُ بِخَيْبَرَ، فَلَمَّا تَبَايَعْنَا رَجَعْتُ عَلَى عَقِبِي حَتَّى خَرَجْتُ مِنْ بَيْتِهِ، خَشْيَةَ أَنْ يُرَادَّنِي الْبَيْعَ، وَكَانَتِ السُّنَّةُ أَنَّ الْمُتَبَايِعَيْنِ بِالْخِيَارِ حَتَّى يَتَفَرَّقَا، قَالَ عَبْدُ اللَّهِ فَلَمَّا وَجَبَ بَيْعِي وَبَيْعُهُ رَأَيْتُ أَنِّي قَدْ غَبَنْتُهُ بِأَنِّي سُقْتُهُ إِلَى أَرْضِ ثَمُودٍ بِثَلاَثِ لَيَالٍ وَسَاقَنِي إِلَى الْمَدِينَةِ بِثَلاَثِ لَيَالٍ‏.‏

Narrated Abdullah bin Umar(R.A) I bartered my property in khaiber to Usman ( cheif of the faithful beleivers) for his property in Al-Wadi.When we finished the deal,I left immediately and got out of his house lest he should cancel the deal, for the tradition was that the buyer and the seller had the option of cancelling the bargain unless they seperated.When our deal was completed, I came to know that I had been unfair to Uthman, for by selling him my land I caused him to be in the land of Thamud,at a distance of three days journy from Madinah while he made me nearer to Madinah, at a distance of three days journy from my former land.