Sa'd ibn Ubadah
Muhammad sent Sa'd ibn Ubadah and Sa'd ibn Muadh to investigate rumours that the Jews of the Qurayza tribe were planning to abandon the defence and join the besiegers. The two Sa'ds found that the situation was even worse than they had imagined, for the Jews denied that they had ever had a treaty with Muhammad. Sa'd ibn Ubadah insulted the Jews to their faces, and they, after reminding the messengers of past favours between their tribes, insulted him back, defaming Muhammad and the Muslims "with the ugliest of words". Sa'd ibn Ubadah became "violently angry". Sa'd ibn Mu'adh had to restrain his friend, "for the dispute between us is too serious for recrimination. It is the sword." They reported back to Muhammad with the enigmatic message: "Adal and al-Qara!" referring to an incident of treachery a couple of years earlier. Muhammad only answered, "God is greater! Be of good cheer, you Muslims."