‘Imrān ibn Husayn (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) saw a man wearing a brass ring on his hand and said: “What is that?” The man said: “It is for a weakening ailment.” He said: “Take it off, for it will only increase your weakness. If you die with it on, you will never succeed.”
‘Imrān ibn Husayn, (may Allah be pleased with him) relates a situation of the Prophet (may Allah's peace and blessings be upon him) in regard to combating polytheism and saving people from it. In that situation, he saw a man wearing a ring made of yellow brass, so he asked him about the reason he was wearing it. The man replied that he was wearing it to keep pain away from him. So, the Prophet (may Allah's peace and blessings be upon him) ordered him to immediately remove it. He also told him that it would harm, rather than benefit, him. Indeed, it would worsen the ailment that it was worn for. Even worse, if the man kept wearing it until he dies, he would be deprived of success in the Hereafter.