Sulaiman ibn Dawud al-Hashimi narrated to us, Isma'il—meaning ibn Ja'far—narrated to us, al-'Ala'—meaning ibn 'Abd al-Rahman—informed me, from Ma'bad ibn Ka'b al-Salmi, from his brother 'Abdullah ibn Ka'b, from Abu Umamah, that the Prophet, peace and blessings be upon him, said: "Whoever seizes the right of a Muslim man by his oath, Allah has made the Fire obligatory for him and forbidden Paradise to him." A man said to him, "Even if it is something insignificant, O Messenger of Allah?" He said, "Even if it is a twig from an arak tree!"
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 24009/56