Abu Ramthah (may Allah be pleased with him) reported that he said to the Prophet (may Allah’s peace and blessings be upon him): Show me this thing on your back (to treat it), for I am a physician. The Prophet (may Allah's peace and blessings be upon him) replied: "Allah is the Physician. You are only a kind man. The one who heals it is the One who created it. [Abu Dawood]

"عن أبي رَمْثة -رضي الله عنه- أنَّه قال للنبي -صلى الله عليه وسلم-: أَرِني هذا الذي بظهرك، فإنِّي رجلٌ طبيبٌ، قال: «اللهُ الطبيبُ، بل أنت رجلٌ رَفِيقٌ، طبيبُها الذي خلقَها». [صحيح.] - [رواه أبو داود وأحمد.]"