Muhammad, the narrator, reports that there was a disagreement between Sayyiduna Umar ibn Khattab and Sayyiduna Mu'adh ibn Afra regarding something. Both of them appointed Sayyiduna Ubayy ibn Ka'b as an arbitrator. Sayyiduna Umar (may Allah be pleased with him) narrated the entire incident to him. Sayyiduna Ubayy said: "You should pardon the Commander of the Faithful." He replied: "If this payment is obligatory upon me, then do not pardon me at all." So Sayyiduna Ubayy ibn Ka'b said: "O Commander of the Faithful! This payment is indeed obligatory upon you." Then Sayyiduna Umar (may Allah be pleased with him) swore an oath and said: "Because of my swearing, I am absolved of it; you take this thing, it is yours."