Musnad Ahmad 760:7

Sufyan ibn 'Uyaynah narrated to us, from Isma'il, that he heard Qays say: I heard al-Sunabihi al-Ahmasi say: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "Behold, I am your forerunner at the Basin (al-Hawd), and I will vie with you in numbers against the nations, so do not fight one another after me."