Musnad Ahmad 539:2

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Yazid ibn Khumayr, from Shurahbil ibn Shuf‘ah, who said: The plague occurred, and ‘Amr ibn al-‘As said: "It is an impurity (rijs), so disperse from it." This reached Shurahbil ibn Hasanah, so he said: "I have accompanied the Messenger of Allah, may Allah bless him and grant him peace, and ‘Amr is more misguided than the camel of his family. It is the supplication of your Prophet, the mercy of your Lord, and the death of the righteous before you. So gather for it, and do not disperse from it." This reached ‘Amr ibn al-‘As, and he said: "He has spoken the truth."