Yahya related to me from Malik that he had heard from Bukayr ibn Abdullah ibn al-Ashajj from Ibn Atiya that the Messenger of Allah ﷺ said, "There is no contagion, no hama and no serpent in a hungry belly. However, the possessor of sick livestock must not stop at the same place as the possessor of healthy livestock, but the possessor of healthy livestock may stop wherever he wishes." They said, "Messenger of Allah, Why is that?" The Messenger of Allah ﷺ said, "It is harmful." 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.