Maliks Muwatta Book 43, Hadith Number 14.

Section : Killing Secretly by Trickery and Sorcery.

Yahya related to me from Malik from Muhammad ibn Abd ar-Rahman ibn Sad ibn Zurara that he had heard that Hafsa, the wife of the Prophet, may Allah bless him and grant him peace, killed one of her slave-girls who had used sorcery against her. She was a mudabbara. Hafsa gave the order, and she was killed.

Malik said, “The sorcerer is the one who uses sorcery for himself and no one else uses that for him. It is like the one about whom Allah, the Blessed, the Exalted, said in His Book, ‘They know the one who devotes himself to it will have no share in the Next World.’ (Sura 2 ayat 102) I think that that person is killed if he does that himself.”