Maliks Muwatta Book 50, Hadith Number 12.
Section : Treating the Invalid.
Yahya related to me from Malik from Zayd ibn Aslam that a man received a wound in the time of the Messenger of Allah, may Allah bless him and grant him peace. The blood clotted in the wound and the man called two men from the Banu Ammar tribe. They looked at it and claimed that the Messenger of Allah, may Allah bless him and grant him peace, said to them, “Which of you is the better doctor?” They said, “Is there any good in medicine, Messenger of Allah?” Zayd claimed that the Messenger of Allah, may Allah bless him and grant him peace, said, “The one who sent down the disease sent down the remedy.”