Sayyiduna Abu Waqid al-Laythi (may Allah be pleased with him) said: I was sitting with the Messenger of Allah (peace and blessings be upon him), my knee touching his (peace and blessings be upon him) knee, when someone came and said something into his (peace and blessings be upon him) ear. The face of the Messenger of Allah (peace and blessings be upon him) changed, and the blood rushed up to the lines of his (peace and blessings be upon him) forehead. Then he (peace and blessings be upon him) said: "This is the messenger of Amir bin al-Tufayl; he threatens me and those around me. But Allah has sufficed me against him through the sons from the descendants of Isma'il, the two sons of Qaylah." Hisham (may Allah have mercy on him) said: "That is, the Ansar are meant."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3286