Bulugh al-Maram 13:7

Narrated 'Abdullah bin 'Amr (RA):

A desert Arab came to the Prophet (ﷺ) and said, "O Allah's Messenger, what are the major sins?" The narrator reported the Hadith and it contains: "The false oath." It contains also: I asked, "What is the false oath?" The Prophet (ﷺ) replied, "It is that (oath) by which one takes possession of the property of a Muslim person, while he is lying." [al-Bukhari reported it].