Sayyiduna Abdullah bin Abi Awfa (may Allah be pleased with him) narrates: Sayyiduna Jibril (peace be upon him) came to the Prophet (peace and blessings be upon him) when his (peace and blessings be upon him) Companions had become exhausted, and he (peace and blessings be upon him) was washing his head. He said: "O Muhammad! You have put down your weapons, whereas the angels have not yet put down their weapons." So the Prophet (peace and blessings be upon him) stopped washing his head before he had finished washing it. Then they went to Banu al-Nadir, and Allah Almighty granted him victory over them (i.e. Banu al-Nadir).
Al-Tabarani recorded it; its chain contains Nu'aym bin Hibban, who is da'if (weak); Ibn Hibban declared him thiqah (trustworthy), and he says: "He makes mistakes."