The Meccan Revelations: Page 759 from Volume One

As for the wisdom of sanctifying Medina , it is because God linked the martyrdom to the prophecy of Muhammad, may God bless him and grant him peace, and his message with the testimony of monotheism as an honor for him, and that faith cannot be achieved without them. It is forbidden as God has forbidden. Then God is a Witr, and He loves the Witr, and He interceded the sanctity of the Sanctuary with the sanctity of Medina, so He made a third sanctuary for the Witr, and made its prohibition for God, not for the Prophet, may God bless him and grant him peace, because it is the Witr, and for this reason he did not forbid except what is adjacent to Mecca. It is declared that the sanctity for God in it is like the sanctity for Mecca, and for this reason he said, forbidden, forbidden. By God, we have mentioned this from the hadiths mentioned in the Two Sanctuaries and the Third Sanctuary that I perform Witr between.