Usama bin 'Umayr al-Hadhali · The Book of Greetings

Plague is the sign of a calamity with which Allah, the Exalted and Glorious, affects people from His servants. So when you hear about it, don't enter there (where it has broken out), and when it has broken out in a land and you are there, then don't run away from it.

Plague is a calamity which was inflicted on those who were before you, or upon Bani Isra'il. So when it has broken out in a land, don't run out of it, and when it has spread in a land, then don't enter it.

This calamity or illness was a punishment with which were punished some of the nations before you. Then it was left upon the earth. It goes away once and comes back again. He who heard of its presence in a land should not go towards it, and he who happened to be in a land where it had broken out should not fly from it.