Sahih Muslim Book 1, Hadith Number 252.

Chapter : Warning for one appropriating the right of a Muslim by taking a false oath: the fire (of Hell) is his chastisement.

It is narrated on the authority of Abu Umama that the Messenger of Allah (may peace be upon him) observed: He who appropriated the right of a Muslim by (swearing a false) oath, Allah would make Hell-fire necessary for him and would declare Paradise forbidden for him. A person said to him: Messenger of Allah, even if it is something insignificant? He (the Holy Prophet) replied:(Yes)even if it is the twig of the arak tree.