"The Messenger of Allah ﷺ said: 'There is no 'Adwa (contagion), no Tiyarah (evil omen) and no Hamah.' A Bedouin man stood up and said: 'O Messenger of Allah, what do you think about a camel that suffers from mange and then all other camels get mange?' He said: 'That is because of the Divine Decree. How else did the first one get mange?'" Note: The majority of scholars interpret this to mean that these things in and of themselves do not transmit or cause harm through supernatural or hidden means but that Allah is ultimately in control and any fearful superstition around these is false.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ عَدْوَى وَلاَ طِيَرَةَ وَلاَ هَامَةَ فَقَامَ إِلَيْهِ رَجُلٌ أَعْرَابِيٌّ فَقَالَ يَا رَسُولَ اللَّهِ أَرَأَيْتَ الْبَعِيرَ يَكُونُ بِهِ الْجَرَبُ فَيُجْرِبُ الإِبِلَ كُلَّهَا قَالَ ذَلِكُمُ الْقَدَرُ فَمَنْ أَجْرَبَ الأَوَّلَ  

“The Messenger of Allah ﷺ said: ‘There is no ‘Adwa, no omen, and no Hamah.’ A man stood up and said: ‘O Messenger of Allah, what if a camel has mange and another camel gets mange from it?’ He said: ‘That is the Divine decree. Who causes the mange in the first one?’” (Using translation from Ibn Mājah 3540)  

قَالَ رَسُولُ اللهِ ﷺ لَا عَدْوَى وَلَاطِيَرَةَ وَلَا هَامَةَ قَالَ فَقَامَ إِلَيْهِ رَجُلٌ فَقَالَ يَا رَسُولَ اللهِ أَرَأَيْتَ الْبَعِيرَ يَكُونُ بِهِ الْجَرَبُ فَتَجْرَبُ الْإِبِلُ قَالَ ذَلِكَ الْقَدَرُ فَمَنْ أَجْرَبَ الْأَوَّلَ