Sahih Bukhari | Volume 7 | Hadith Number 615

Narrated by Abu Huraira
Allah's Apostle said, 'There is no 'Adha (no disease is conveyed from the sick to the healthy without Allah's permission), nor Safar, nor Hama." A bedouin stood up and said, "Then what about my camels? They are like deer on the sand, but when a mangy camel comes and mixes with them, they all get infected with mangy." The Prophet said, "Then who conveyed the (mange) disease to the first one?"