Abd al-Rahman bin Ghanm (may Allah have mercy on him) said: The plague broke out in Syria, and Sayyiduna Amr bin al-As (may Allah be pleased with him) addressed us and said: This plague is a filth, so flee from it into the valleys and mountain passes. This reached Sayyiduna Shurahbil Ibn Hasanah (may Allah be pleased with him), and he said: Amr has spoken falsely. I accompanied the Messenger of Allah (peace and blessings be upon him), and Amr is more astray than his family's donkey. Rather, it is the mercy of your Lord, the supplication of your Prophet, and the death of the righteous before you.
Hadith Referenceالمعجم الكبير للطبراني / باب الشين / 7178