Sahih Muslim: Book 39, Hadith 136

‘Abdullah b. ‘Abbas reported: Umar b. Khattab set out for Syria. As he came at Sargh (a town by the side of Hijaz on the way to Syria), there met him the commander of the forces, Abu Ubaida b. Jandb, and his companions. They informed him that a scourge had broken out in Syria. Ibn ‘Abbas further reported that ‘Umar said: Call to me tile earliest emigrants. So I called them. He (Hadrat ‘Umar) sought their advice, and they told him that the scourge had broker, out in Syria. There was a difference of opinion (whether they should proceed further or go back to their homes in such a situation). Some of them said: You (‘Umar) have set forth for a task, and, therefore, we would not advise you to go back, whereas some of them said: You have along with you the remnants (of the sacred galaxy) of men and (the blessed) Companions of Allah’s Messenger (ﷺ), so we would not advise you to go forth towards this calamity (with such eminent persons and thus expose them deliberately to a danger). He (Hadrat ‘Umar) said: You can now go away. He said: Call to me the Ansar. So I called them to him, and he consulted them, and they trod the same path as was trodden by the Muhajirin, and they differed in their opinions as they had differed. He said: Now, you can go. He again said: Call to me the old persons of the Quraish who had migrated before the Victory (that is the Victory of Mecca), so I called them (and Hadrat ‘Umar consulted them) and not even two persons differed (from the opinion held by the earlier delegates). They said: Our opinion is that you better go back along with the people and do not make them go to this scourge, So ‘Umar made announcement to the people: In the morning I would be on the back of my side. So they (set forth in the morning), whereupon Abu ‘Ubaida b. Jarrah said: Are you going to run away from the Divine Decree? Thereupon ‘Umar said: Had it been someone else to say this besides you! ‘Umar (in fact) did not approve of his opposing (this decision) and he said: Yes, we are running from the Divine Decree (to the) Divine Decree. You should think if there had been camels for you and you happened to get down in a valley having two sides, one of them covered with verdure and the other being barren, would you not (be doing) according to the Divine Decree if you graze them in verdure? And in case you graze them in the barren land (even then you would be grazing them) according to the Divine Decree.
There happened to come ‘Abd al-Rahman b. ‘Auf and he had been absent in connection with some of his needs. He said: I have with me a knowledge of it, that I heard Allah’s Messenger (ﷺ) as saying: If you hear of its presence (the presence of plague) in a land, don’t enter it, but if it spreads in the land where you are, don’t fly from it. Thereupon ‘Umar b. Khattab praised Allah and then went back?