A voice went forth from heaven saying; Sinner, son of sinner, descendant of Esau the
sinner, I have a tiny creature in my world called a gnat. (Why is it called a tiny creature? Because it has an orifice for taking in but not for excreting.) Go up on the dry land and make war with it. When he landed the gnat came and entered his nose, and it knocked against his brain for seven years. One day as he was passing a blacksmith’s it heard the noise of the hammer and stopped. He said; I see there is a remedy. So every day they brought a blacksmith who hammered before him. If he was a non-Jew they gave him four zuz, if he was a Jew they said, It is enough that you see the suffering of your enemy. This went on for thirty days, but then the creature got used to it.
Gittin 56b
h/t Jonathan L. M.@TheLordGave
