Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) says: A Bedouin came to the Prophet (peace and blessings be upon him) and asked: What are the major sins? He (peace and blessings be upon him) said: "Associating partners with Allah." He asked: Then what? He (peace and blessings be upon him) said: "Disobedience to parents." He asked: Then which? He (peace and blessings be upon him) said: "The false oath." The narrator says: I said to Amir: What is the false oath? He said: Seizing a Muslim's wealth by means of a false oath.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 19868