The father of Abu Khuzamah (may Allah be pleased with him) narrates from the Prophet (peace and blessings be upon him) that (he asked): O Messenger of Allah! What do you think of the medicine we treat ourselves with, the ruqyah we seek, and the things we use for protection; can these avert anything of Allah's decree? Then he (peace and blessings be upon him) said: "These too are from Allah's decree."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19598