The Prophet ﷺ said, 'No 'Adwa (i.e. no contagious disease is conveyed to others without Allah's permission); nor (any evil omen in the month of) Safar; nor Hama" A bedouin said, "O Messenger of Allah ﷺ! What about the camels which, when on the sand (desert) look like deers, but when a mangy camel mixes with them they all get infected with mange?" On that Allah s Apostle said, "Then who conveyed the (mange) disease to the first (mangy) camel?"  

قَالَ النَّبِيُّ ﷺ لاَ عَدْوَى وَلاَ صَفَرَ وَلاَ هَامَةَ فَقَالَ أَعْرَابِيٌّ يَا رَسُولَ اللَّهِ فَمَا بَالُ الإِبِلِ تَكُونُ فِي الرَّمْلِ كَأَنَّهَا الظِّبَاءُ فَيُخَالِطُهَا الْبَعِيرُ الأَجْرَبُ فَيُجْرِبُهَا فَقَالَ رَسُولُ اللَّهِ ﷺ فَمَنْ أَعْدَى الأَوَّلَ  

Messenger of Allah ﷺ said: The cattle (sheep, cows, camels, etc.) suffering from a disease should not be mixed up with healthy cattle, (or said: "Do not put a patient with a healthy person ). " (as a precaution).  

قَالَ النَّبِيُّ ﷺ لاَ يُورِدَنَّ مُمْرِضٌ عَلَى مُصِحٍّ وَأَنْكَرَ أَبُو هُرَيْرَةَ حَدِيثَ الأَوَّلِ قُلْنَا أَلَمْ تُحَدِّثْ أَنَّهُ لاَ عَدْوَى فَرَطَنَ بِالْحَبَشِيَّةِ قَالَ أَبُو سَلَمَةَ فَمَا رَأَيْتُهُ نَسِيَ حَدِيثًا غَيْرَهُ