Narrated 'Abdullah bin Abu Aufa (Radi-Allahu 'anhu):

A man displayed some goods in the market and swore by Allah SWT that he had
been offered so much for that, that which was not offered, and he said so,
so as to cheat a Muslim. On that occasion the following Verse was revealed:
"Verily! Those who purchase a small gain at the cost of Allah's covenant
and their oaths (They shall have no portion in the Hereafter ..etc.)'
(3.77)

Bukhari Vol. 3 : No. 301