Roite bindele. It’s B.S. and no legitimate source.
That said, it’s a an OLD tradition. My great-great grandmother used to wear one on her left hand. Some B.S. regarding the evil eye.
Peasant stuff. Witchcraft posing as Judaism.
Old grandmothers in my family would light a small piece of dried palm frond when there was lightning. Said the smoke would confuse the devil and keep us safe. I'd look at that little wisp of smoke and have the kind of feeling you probably had about your great grandmother...