What is the cause of plagues and epidemics, and what is the meaning of the Hadith, "There are five [things] if you are afflicted by them—and I seek refuge with Allah that you should live to see them"?

The emergence of widespread epidemics is linked to the actions of people and their defiance of God's commands, as stated in the Almighty's words: ﴿And whatever affliction befalls you, it is because of what your hands have earned, and He pardons much.﴾, and His saying: ﴿Corruption has appeared on land and sea by [reason of] what the hands of people have earned so that He may let them taste part of [the consequence of] what they have done that perhaps they will return.﴾

The Prophet (peace be upon him) mentioned that the prevalence of immorality leads to plagues and pains, and the shortage in measure and weight brings drought and the oppression of rulers. Withholding zakat prevents rain, breaking covenants empowers enemies, and not ruling by the Book of Allah causes strife among people. These punishments are of the same nature as the sins, for the recompense of a deed is of its own kind.