According to the folk calendar - Kupriyan and Ustinya

The holiday is associated with the names of the martyrs Cyprian and Justina According to popular beliefs, on this day it was possible to get rid of evil spells It is not for nothing that October 15 was sometimes called the Day of Purification from Obsessions Usually women turned to Ustinya in prayer, and men to Cuprian You couldn’t quarrel with Kupriyan, otherwise you could bring trouble on yourself