Sahih Bukhari Volume 7, Book 71, Hadith Number 625.
Narrated By ‘Abdullah bin ‘Abbas : ‘Umar bin Al-Khattab departed for Sham and when he reached Sargh, the commanders of the (Muslim) army, Abu ‘Ubaida bin Al-Jarrah and his companions met him and told him that an epidemic had broken out in Sham. ‘Umar said, “Call for me the early emigrants.” So ‘Umar called them, consulted them and informed them that an epidemic had broken out in Sham. Those people differed in their opinions. Some of them said, “We have come out for a purpose and we do not think that it is proper to give it up,” while others said (to ‘Umar), “You have along with you. other people and the companions of Allah’s Apostle so do not advise that we take them to this epidemic.” ‘Umar said to them, “Leave me now.” Then he said, “Call the Ansar for me.” I called them and he consulted them and they followed the way of the emigrants and differed as they did. He then said to them, Leave me now,” and added, “Call for me the old people of Quraish who emigrated in the year of the Conquest of Mecca.” I called them and they gave a unanimous opinion saying, “We advise that you should return with the people and do not take them to that (place) of epidemic.” So ‘Umar made an announcement, “I will ride back to Medina in the morning, so you should do the same.” Abu ‘Ubaida bin Al-Jarrah said (to ‘Umar), “Are you running away from what Allah had ordained?” ‘Umar said, “Would that someone else had said such a thing, O Abu ‘Ubaida! Yes, we are running from what Allah had ordained to what Allah has ordained. Don’t you agree that if you had camels that went down a valley having two places, one green and the other dry, you would graze them on the green one only if Allah had ordained that, and you would graze them on the dry one only if Allah had ordained that?” At that time ‘Abdur-Rahman bin ‘Auf, who had been absent because of some job, came and said, “I have some knowledge about this. I have heard Allah’s Apostle saying, ‘If you hear about it (an outbreak of plague) in a land, do not go to it; but if plague breaks out in a country where you are staying, do not run away from it.’ ” ‘Umar thanked Allah and returned to Medina.