Book of Conditions Sih alBukhari ...
(from the companions of All''s Messenger (ﷺ)) When Suhail bin `Amr agreed to the Treaty (of Hudaibiya), one of the things he stipulated then, was that the Prophet (ﷺ) should return to them ( the pagans) anyone coming to him from their side, even if he was a Muslim; and would not interfere between them and that person.