Sahih Muslim 2219 a
'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?
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ عَبْدِ،
 الْحَمِيدِ بْنِ عَبْدِ الرَّحْمَنِ بْنِ زَيْدِ بْنِ الْخَطَّابِ عَنْ عَبْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ الْحَارِثِ بْنِ نَوْفَلٍ،
 عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّ عُمَرَ بْنَ الْخَطَّابِ، خَرَجَ إِلَى الشَّامِ حَتَّى إِذَا كَانَ بِسَرْغَ لَقِيَهُ
 أَهْلُ الأَجْنَادِ أَبُو عُبَيْدَةَ بْنُ الْجَرَّاحِ وَأَصْحَابُهُ فَأَخْبَرُوهُ أَنَّ الْوَبَاءَ قَدْ وَقَعَ بِالشَّامِ ‏.‏ قَالَ
 ابْنُ عَبَّاسٍ فَقَالَ عُمَرُ ادْعُ لِيَ الْمُهَاجِرِينَ الأَوَّلِينَ ‏.‏ فَدَعَوْتُهُمْ فَاسْتَشَارَهُمْ وَأَخْبَرَهُمْ
 أَنَّ الْوَبَاءَ قَدْ وَقَعَ بِالشَّامِ فَاخْتَلَفُوا فَقَالَ بَعْضُهُمْ قَدْ خَرَجْتَ لأَمْرٍ وَلاَ نَرَى أَنْ تَرْجِعَ
 عَنْهُ ‏.‏ وَقَالَ بَعْضُهُمْ مَعَكَ بَقِيَّةُ النَّاسِ وَأَصْحَابُ رَسُولِ اللَّهِ صلى الله عليه وسلم وَلاَ نَرَى
 أَنْ تُقْدِمَهُمْ عَلَى هَذَا الْوَبَاءِ ‏.‏ فَقَالَ ارْتَفِعُوا عَنِّي ‏.‏ ثُمَّ قَالَ ادْعُ لِيَ الأَنْصَارَ فَدَعَوْتُهُمْ لَهُ
 فَاسْتَشَارَهُمْ فَسَلَكُوا سَبِيلَ الْمُهَاجِرِينَ وَاخْتَلَفُوا كَاخْتِلاَفِهِمْ ‏.‏ فَقَالَ ارْتَفِعُوا عَنِّي ‏.‏ ثُمَّ
 قَالَ ادْعُ لِي مَنْ كَانَ هَا هُنَا مِنْ مَشْيَخَةِ قُرَيْشٍ مِنْ مُهَاجِرَةِ الْفَتْحِ ‏.‏ فَدَعَوْتُهُمْ فَلَمْ يَخْتَلِفْ
 عَلَيْهِ رَجُلاَنِ فَقَالُوا نَرَى أَنْ تَرْجِعَ بِالنَّاسِ وَلاَ تُقْدِمْهُمْ عَلَى هَذَا الْوَبَاءِ ‏.‏ فَنَادَى عُمَرُ
 فِي النَّاسِ إِنِّي مُصْبِحٌ عَلَى ظَهْرٍ فَأَصْبِحُوا عَلَيْهِ ‏.‏ فَقَالَ أَبُو عُبَيْدَةَ بْنُ الْجَرَّاحِ أَفِرَارًا
 مِنْ قَدَرِ اللَّهِ فَقَالَ عُمَرُ لَوْ غَيْرُكَ قَالَهَا يَا أَبَا عُبَيْدَةَ - وَكَانَ عُمَرُ يَكْرَهُ خِلاَفَهُ - نَعَمْ
 نَفِرُّ مِنْ قَدَرِ اللَّهِ إِلَى قَدَرِ اللَّهِ أَرَأَيْتَ لَوْ كَانَتْ لَكَ إِبِلٌ فَهَبَطْتَ وَادِيًا لَهُ عِدْوَتَانِ إِحْدَاهُمَا
 خَصْبَةٌ وَالأُخْرَى جَدْبَةٌ أَلَيْسَ إِنْ رَعَيْتَ الْخَصْبَةَ رَعَيْتَهَا بِقَدَرِ اللَّهِ وَإِنْ رَعَيْتَ الْجَدْبَةَ رَعَيْتَهَا
 بِقَدَرِ اللَّهِ قَالَ فَجَاءَ عَبْدُ الرَّحْمَنِ بْنُ عَوْفٍ وَكَانَ مُتَغَيِّبًا فِي بَعْضِ حَاجَتِهِ فَقَالَ إِنَّ عِنْدِي
 مِنْ هَذَا عِلْمًا سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏
"‏ إِذَا سَمِعْتُمْ بِهِ بِأَرْضٍ فَلاَ
 تَقْدَمُوا عَلَيْهِ وَإِذَا وَقَعَ بِأَرْضٍ وَأَنْتُمْ بِهَا فَلاَ تَخْرُجُوا فِرَارًا مِنْهُ ‏"‏ ‏.‏ قَالَ فَحَمِدَ اللَّهَ عُمَرُ
 بْنُ الْخَطَّابِ ثُمَّ انْصَرَفَ ‏.‏