What is the ruling on hair transplantation in the beard if it is deficient?

It is not permissible to implant beard hair unless it is for the purpose of treatment and removing a temporary defect caused by an illness or accident that led to its disfigurement. This is because implanting it for any other reason is considered altering Allah's creation. The evidence for the permissibility of cosmetic procedures to remove a temporary defect is what was narrated by Abu Dawud, Al-Tirmidhi, and Al-Nasa'i from Arfajah ibn As'ad, whose nose was cut off and he fashioned a nose of gold by the command of the Prophet, peace and blessings be upon him. However, if the beard is naturally sparse, it is not permissible to increase its density through implantation, because that is not part of the commanded act of growing the beard, and it is considered altering Allah's creation.