The ruling on tying a black wool thread around the legs for treatment

Question:
He says: In our country, some of the elderly tie a thread around their legs, a black wool thread. They claim that it cures them of joint disease.

Answer:
This is the same thing. The Prophet (peace and blessings be upon him) saw a brass ring on a man’s leg and asked, “What is this?” He said, “It is for the washanah,” meaning the fever; it protects from the fever. He said, “Remove it, for it will only increase your affliction. If you were to die while it is on you, you would never succeed.” This is not permissible, not on the leg, not on the hand, not on the finger, and not on the neck. This is not permissible.

Question:
He says: Honorable Shaykh, may Allah grant you success. He says: I bought a new car.

Answer:
Note the difference between medical matters and matters of belief. If the doctors decide that he should put something on his body as a form of treatment, there is nothing wrong with it; this is medically what it is. But if he puts it on believing that it brings benefit and harm, and that it prevents the evil eye, prevents fever, prevents such and such, that is shirk (associating partners with Allah). Yes.