Sahih Bukhari

Narrated Abu Huraira: 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 Allah's Messenger (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?