Umm Salama reported God’s Messenger as saying, “I am only a human being and you bring your disputes to me, some perhaps being more eloquent in their plea than others, so that I give judgment on their behalf according to what I hear from them. Therefore whatever I decide for anyone which by right belongs to his brother he must not take, for I am granting him only a portion of hell.”
Abu Umama reported God’s Messenger as saying, “If anyone appropriates by his oath what rightly belongs to a Muslim, God has made hell necessary for him and deprived him of paradise.” A man asked God’s Messenger whether that applied even if it were a small amount, and he replied, “Even if it were a stick from an arak tree.”
Ibn Mas'ud reported God’s Messenger as saying, “If anyone swears a firm oath, 1 acting wickedly thereby, and appropriates by it property belonging to a Muslim, God will be angry when he meets Him on the day of resurrection.” And God has sent down the verification of that, “Those who barter for a small price God's covenant and their oaths”2.
(Bukhari and Muslim.)
1. Or an oath he is compelled to take.
2. Al-Qur’an, 3:77
