Sayyiduna Umar (may Allah be pleased with him) set out for Syria (Sham). When he reached Sargh, news reached him that an epidemic had broken out in Syria, and Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) informed him that the Messenger of Allah (peace and blessings be upon him) said: "When you hear of it in a land, do not go there; and when the epidemic breaks out in a place where you are present, do not leave it with the intention of fleeing from it." So Sayyiduna Umar (may Allah be pleased with him) turned back from Sargh. Ibn Shihab narrates from Salim bin Abdullah, who narrates from his father (Sayyiduna Abdullah bin Umar, may Allah be pleased with them both), that Sayyiduna Umar (may Allah be pleased with him) turned back with the people because of the hadith of Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنائز / 6556