Umar bin Abd al-Aziz (may Allah have mercy on him) says: For a wound that is not bone-exposing, such as a scratch and the like, there is settlement; and Sayyiduna Mu'adh and Sayyiduna Umar (may Allah be pleased with them both) fixed only the physician's fee for a non-exposing wound.
There is also a marfu' narration from Sayyiduna Mu'adh (may Allah be pleased with him): "For a bone-exposing wound in which the bone becomes visible there are five camels, and for any wound less than that, it is in proportion to it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16210