Muwatta Malik #1744

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."