Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: A Bedouin came to the service of the Prophet (peace and blessings be upon him). He asked: O Messenger of Allah, what is the major sin? The Prophet (peace and blessings be upon him) said: Associating partners with Allah. He asked: Then which one? He said: Then disobedience to parents. He asked: Then which one? He said: Then taking a false oath.
The narrator states: I asked my teacher Amir, what is meant by "Yameen Ghamus"? He replied: It is when a person takes a false oath and thereby usurps the wealth of a Muslim.