Muwatta Malik, Book 45, Hadith 1622 (In-Book)

Yahya related to me from Malik from Muhammad ibn al-Munkadir and from Salim ibn Abi'n-Nadr, the mawla of Umar ibn Ubaydullah that Amir ibn Sad ibn Abi Waqqas heard his father ask Usama ibn Zayd, "Have you heard anything from the Messenger of Allah, may Allah bless him and grant him peace, about the plague?" Usama said, "The Messenger of Allah, may Allah bless him and grant him peace, said, 'The plague is a punishment that was sent down on a party of the Banu Israil or whoever was before them. When you hear of it in a land, do not enter it. If it comes upon a land and you are in it, do not depart in flight from it.' " Malik said that Abu'n-Nadr said, "That is, do not depart with no other intention but flight."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ، وَعَنْ سَالِمٍ أَبِي النَّضْرِ، مَوْلَى عُمَرَ بْنِ عُبَيْدِ اللَّهِ عَنْ عَامِرِ بْنِ سَعْدِ بْنِ أَبِي وَقَّاصٍ، عَنْ أَبِيهِ، أَنَّهُ سَمِعَهُ يَسْأَلُ، أُسَامَةَ بْنَ زَيْدٍ مَا سَمِعْتَ مِنْ، رَسُولِ اللَّهِ صلى الله عليه وسلم فِي الطَّاعُونِ فَقَالَ أُسَامَةُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ الطَّاعُونُ رِجْزٌ أُرْسِلَ عَلَى طَائِفَةٍ مِنْ بَنِي إِسْرَائِيلَ أَوْ عَلَى مَنْ كَانَ قَبْلَكُمْ فَإِذَا سَمِعْتُمْ بِهِ بِأَرْضٍ فَلاَ تَدْخُلُوا عَلَيْهِ وَإِذَا وَقَعَ بِأَرْضٍ وَأَنْتُمْ بِهَا فَلاَ تَخْرُجُوا فِرَارًا مِنْهُ ‏" ‏ ‏.‏ قَالَ مَالِكٌ قَالَ أَبُو النَّضْرِ لاَ يُخْرِجُكُمْ إِلاَّ فِرَارٌ مِنْهُ ‏.‏

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also referenced under: Book 45, Hadith 23 (USC-MSA)