Sahih al-Bukhari 2675
Narrated `Abdullah bin Abu `Aufa:
A man displayed some goods in the market and took a false oath that he had been offered so much for 
them though he was not offered that amount Then the following Divine Verse was revealed:-- "Verily! 
Those who purchase a little gain at the cost of Allah's covenant and their oaths . . . Will get painful 
punishment." (3.77) Ibn Abu `Aufa added, "Such person as described above is a treacherous Riba eater 
(i.e. eater of usury).
حَدَّثَنِي إِسْحَاقُ، أَخْبَرَنَا يَزِيدُ بْنُ هَارُونَ، أَخْبَرَنَا الْعَوَّامُ، قَالَ حَدَّثَنِي إِبْرَاهِيمُ أَبُو إِسْمَاعِيلَ السَّكْسَكِيُّ، سَمِعَ عَبْدَ اللَّهِ بْنَ أَبِي أَوْفَى ـ رضى الله عنهما ـ يَقُولُ أَقَامَ رَجُلٌ سِلْعَتَهُ فَحَلَفَ بِاللَّهِ لَقَدْ أُعْطِيَ بِهَا مَا لَمْ يُعْطَهَا فَنَزَلَتْ ‏{‏إِنَّ الَّذِينَ يَشْتَرُونَ بِعَهْدِ اللَّهِ وَأَيْمَانِهِمْ ثَمَنًا قَلِيلاً‏}‏ وَقَالَ ابْنُ أَبِي أَوْفَى النَّاجِشُ آكِلُ رِبًا خَائِنٌ‏.‏