Sayyiduna Ka'b (may Allah be pleased with him) says: If I were to commit adultery thirty-three times, I would consider this evil to be lighter than consuming one dirham of usury, while Allah Almighty knows that I am consuming it knowing it to be usury.
Hadith Takhrij«اسناده صحيح الي كعب الاحبار۔ أخرجه الدارقطني: 3/ 16 ، (انظر مسند أحمد ترقيم الرسالة: 21958 ترقیم بيت الأفكار الدولية: 22304»
Brief Explanation
Benefits: … The meaning of the last sentence of the hadith is that Sayyiduna Ka‘b radi Allahu anhu should be certain that he is indeed consuming a dirham of usury (riba).