Evidence from the Sunnah
It was narrated that Aisha (RA) said: The Messenger of Allah was bewitched by a man from Banu Zurayq who was called Labeed ibn Al-A'sam, until the Messenger of Allah imagined that he had done something when he had not done it. One day, or one night, when he was with me he invoked Allah for a long time, then he said:
O Aisha, I feel that Allah has inspired me as to how to cure myself.
Two men came to me; one of them sat at my head and the other at my feet. Then one of them said to the other: 'What is hurting this man?’ the other said: 'He is bewitched. He said: 'Who bewitched him?' The other said: 'Labeed ibn Al-A'sam. He said: 'With what?' The other said: 'With a comb, the hair gathered in it, and the outer skin of the pollen of a male date palm. He said: 'Where is it?' & The other said: 'In the well of Dharwaan."
So the Messenger of Allah went there with some of his Companions, then he came back and said:
O Aishah, it is as if its water is an infusion of henna leaves and the heads of its date palms are like the heads of devils." I said: "O Messenger of Allah, will you not take it out?" He said: "Allah has healed me and I do not like for evil to be spread among the people." And he ordered that the well be filled in. Fath Al-Baari, 10/222
Al-Qurtubi said:
The Qur'an, in more than one Verse, and the Sunnah, in more than one Hadith indicate that witchcraft exists and that it has an effect on the one who is bewitched. Whoever denies that is a disbeliever who rejects what Allah and His Messenger (PBUH) say, and denies something that is well-known.
Moreover, if he denies witchcraft in secret, he is a heretic and if he denies it openly he is an apostate. Then he said: It cannot be denied that witchcraft has an effect on people's hearts, creating love and hatred and instilling evil ideas, causing separation between man and wife, coming between a man and his mental faculties and causing pain and sickness. All of that is known from real life, and denying it is stubbornness.
Sharh Al-Qurtubi Ala Saheeh Muslim, 6/6
Ibn Qudama said:
Witchcraft is something real, some of it may kill and some may cause sickness, and some may separate a man from his wife and prevent him from having intercourse with her (Al-Mughni, 10/106)
Abu Obaid has said: The meaning of Sihr is to show something other than what it is or should be. Whereas Al-Laith has said: Sihr is an action by means of which a person draws closer to the devil, and gets his (the devils) help. Shumar has said that Ibn Aishah said: Sihr is so called in Arabic because it changes health to sickness.
Al-Raazi said that the word Sihr in the Sharia sense applies to everything the cause of which is hidden, and everything that may be imagined as being other than what it is and happens by way of concealment or deceit. When the word is used in a general sense and is not defined, it is usually in a negative sense and the one who does it is condemned. Qissat Al-Sihr wa'l-Sahrah, p25 p133 note 2
According to Ibn Mandhur: When a sahir makes something false appear to be real, or makes something appear to people appear differently from its true form, it means that he has given an object a status other than its real one Lisaan Al-Arab, 4/348, Beirut
Shamir reported on the authority of Ibn Aisha: Arabs have given it the name sihr because, it can transform good health into illness Ibid
According to Al-Fakhr Ar-razT: Sihr is anything the cause of which is hidden, and which appears in a form other than its real one, with the intention to distort the reality of things and deceive. Al-Misbah Al-Munir, 268
According to Ibn Qudama AI-Maqdisi: Sihr is a set of Uqad (knots), & incantations, and words uttered or written, or carried out in such a way as to affect the body of the subject (al-mashur), his heart or mind, without even coming into contact with him/her. The reality of sihr is that there are some types that can kill, cause one to fall ill, or act as an obstacle against a man having sexual intercourse with his wife. Other types can separate spouses, and can make them hate or love each other. Al-Mughni, 10/104
According to Ibn Al-Qayyim: Sihr consists of the effects of evil souls and the reaction of the reluctant forces. Zaad Al-Ma'ad, 4/126
According to ibn Al-Qayyim: Curing a person affected sihr is of two types: