Musannaf Ibn Abi Shayba 13:2183

Abu Bakr narrated to us, he said: Abu Usamah narrated to us, from al-Walid ibn Kathir, from Muhammad ibn Ka'b ibn Malik, that he heard his brother, Abdullah ibn Ka'b, narrating that Abu Umamah al-Harithi narrated to him that he heard the Prophet, may Allah bless him and grant him peace, saying: "No man shall usurp the right of a Muslim man by his oath, except that Allah will forbid Paradise for him and make the Fire mandatory for him." A man from the people said: "O Messenger of Allah, even if it is a trivial thing?" He said: "Even if it is a twig of arak (a tooth-stick)."