All lands are the countries of the Wise.
Therefore, before Grand Sabbat, they test you. They ask you the question that any witch can answer.
Answer correctly, and you get your red thread.
You know what that means, of course.
I tie this knot in Old Hornie's name, they say. Aye, till he fetch thee home again.
Then they bind it around your wrist.
That's your laissez-passer to the Sabbat. Wear it, after, until you get safely home.
(If you wear it until it falls of its own accord, though, Old Hornie will grant you a boon, they say. Best ask wisely. You know his sense of humor.)