Sahih Muslim
The Book on Salutations and Greetings (Kitab As-Salam)
Book Number: 026 / Hadith Number: 5457
'Auf b. Malik Ashja'i reported We practised incantation in the pre-Islamic days and we said: Allah's Messenger. what is your opinion about it? He said: Let me know your incantation and said: There is no harm in the incantation which does not smack of polytheism.