Muhammad bin Ka'b bin Malik narrated that he heard his brother, Abdullah bin Ka'b, narrate that Sayyiduna Abu Umamah bin Tha'labah al-Harithi (may Allah be pleased with him) told him that he heard the Messenger of Allah (peace and blessings be upon him) say: "No man seizes the right of a Muslim by means of his oath except that Allah forbids Paradise to him and makes Hell obligatory for him." A man from among the people said: O Messenger of Allah, even if it is something small? He (peace and blessings be upon him) said: "Even if it is a tooth-stick (miswak) of the arak tree."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 795