Sahih Bukhari Volume 3, Book 48, Hadith Number 841.

Narated By ‘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).