Is it permissible to transplant hair into the beard to improve the appearance of a patchy beard?

Hair transplantation is permissible if the condition causes a clear and very noticeable disfigurement, due to its unparalleled nature, so that the situation returns to moderation. This is not considered altering Allah's creation; rather, it is a permissible treatment. This is evidenced by the Prophet, peace and blessings be upon him, instructing Arfajah ibn As'ad, whose nose was severed, to wear a nose of gold after he was harmed by a silver nose.