Charms also known as Amulets is something like threads which is tied with the paper on which some codes are written. And sometimes a bangle is used and wore around the arms.
It was the practice of the Arabs at the time of Prophet Muhammad (May Allah honour Him and grant Him peace) to wear arm bracelets, bangles, beaded necklaces, shells, etc as charms to avert evil and bring good fortune.
This practice goes against Tawheed Al Ruboobiyah (Maintaining the Lordship of Allah) and attribute the power of giving good to the created things instead of Allah (Glory be to Him).
Emran ibn Husaynرضي الله عنه reported that when the Prophet Muhammad (May Allah honour Him and grant Him peace) saw a brass bangle on a man’s upper arm, he said to him, “Woe be on you! What is this?” The Man replied that it was to protect him from a sickness called al-Waahinah. The Prophet Muhammad (May Allah honour Him and grant Him peace) then said, “Cast it off, for verily it would only increase your weakness. And if you died with it on, you would never succeed.”Collected by Ahmed, Ibn Majah, Ibn Hibban
“Treat each other’s sickness, but do not treat sickness with forbidden things” Sunan Abu Dawood vol 3:3865.
Uqba bin Aamirرضي الله عنه reported that the Prophet Muhammad (May Allah honour Him and grant Him peace) once said, “May Allah cause failure and unrest to whoever wears talisman or puts it on others.” Narrated by Ahmad, 16951and Al Haakim.
Narrated by Ahmad bin 'Uqbah bin 'Amirرضي الله عنه said: I heard the Prophet ((May Allah honour Him and grant Him peace) say: Whoever wears an amulet, Allah will not accomplish (his errands) and whoever carries a bead, Allah will not grant him health and safety. Musnad Ahmad Vol 4:154.
The Prophet’s (May Allah honour Him and grant Him peace) companions strictly followed the Prophet’s commands with regard to charms and amulets. Consequently, there are many recorded incidents in which they openly opposed such practices in the society as well as among their families whenever the appeared. ‘Urah reported that when the Sahaabee, Hudhayfaرضي الله عنه, visited a sick man and saw a bracelet on the man’s upper arm, he pulled it off and broke it. Hudhayfah then recited the ayath “Most of them who believe in Allah commit shirk” (Qur’an.Surah Yousuf 12:106). (Ibn Abee Haatim)
Uqbah (R) reported: "Once a group of men approached the Messenger of Allah (May Allah honour Him and grant Him peace)to give their oaths of allegiance. The Prophet (May Allah honour Him and grant Him peace) accepted the oath from nine but refused one. When he was asked the reason, he (May Allah honour Him and grant Him peace)replied: "Verily, he is wearing an amulet (a charm)." The man put his hand in his cloak, pulled the amulet off and broke it, then made the oath. The Prophet (May Allah honour Him and grant Him peace) said: "Whoever wears an amulet has committed Shirk." Musnad Ahmad Vol 4:156 (16969 Arabic), Al-Haakim: Vol 4:219.This Hadeeth was classed as Saheeh by Shaikh al-Albanee in al-Silsilah al-Saheehah 492.
Allah's Messenger (May Allah honour Him and grant Him peace)said: "He who wears a thing shall be committed to it." Tirmidhi
The Sahabah (May allah be pleased with them) were very strict in regards to charms and omens, whether it be within one's family or outside it. Zaynabرضي الله عنه, the wife of Abdullah Ibn Mas'oud (May allah be pleased with them), reports that once Ibn Mas'oudرضي الله عنه saw a cord of necklace around her neck and asked, 'What is it?' She replied: 'It is a cord in which a spell has been placed to help me.' He snatched it from her neck, broke it and said: "Surely the family of Abdullah has no need for Shirk! I have heard Allah's Messenger (May Allah honour Him and grant Him peace) say: 'Verily spells, talismans and charms are Shirk.'" Abu Dawud 3883, Ibn Majah 3530 and Ahmad Vol 1:381.
Zaynabرضي الله عنه replied: 'Why are you saying this? My eye used to twitch and when I went to so and so, the Jew, he put a spell on it and it stopped twitching.' Ibn Mas'oudرضي الله عنه said: 'Verily, it was only a devil prodding it with his hand, so when you had it bewitched he left it. It would have been sufficient for you to say:
Transliteration: "Az-habil-ba's Rabban-naas washfi antash-shafee Laa shifaa' illa shifaa'uk shifaa'aan laa yughaadiruhu saqama". Meaning "Remove the suffering, O Lord of mankind and heal it perfectly as You are the True Healer. There is no cure except Your cure; a cure which is not followed by sickness." Sahih Al Muslim 5434, Sunan Abu Dawud 3874; Ibn Maajah, 3530. Classed as Saheeh by al-Albanee in al-Silsilat al-Saheehah 331 and 2972.
A sick person can resort to permissible means of treatment like medicines, the Messenger of Allah (May Allah honour Him and grant Him peace) said: "Seek treatment, because Allah did not create a sickness but has created a treatment for it, except for old age." Abu Dawud and Authenticated by Shaikh al-Albanee in Saheeh al-Jami no: 29302. In this context, magnetic belts, etc., which have been medically proven to have health benefits can be used for treatment. They do not fall under the category of charms and omens.
The act of the Prophet (May Allah honour Him and grant Him peace) is that a man should supplicate Allah (Glory be to Him)by invoking the Names and Attributes of Allah (Glory be to Him) as mentioned in Al-Fatawa Al-Hadithiyah by Ibn Hajar Al-Haithami Al-Makki, page 88.