Sahih al-Bukhari 5981
Good Manners and Form (Al-Adab)
To be good to one's brother who is a Mushrik
Narrated Ibn `Umar: My father, seeing a silken cloak being sold, said, "O Allah's Messenger (ﷺ) ! Buy this and wear it on Fridays and when the foreign delegates pay a visit to you." He said, "This is worn only by that person who will have no share in the Hereafter." Later a few silken cloaks were given to the Prophet (ﷺ) as a gift, and he sent one of those cloaks to `Umar. `Umar said (to the Prophet), "How can I wear it while you have said about it what you said?" The Prophet (ﷺ) said, "I did not give it to you to wear but to sell or to give to someone else to wear." So `Umar sent it to his (pagan) brother who was from the inhabitants of Mecca before he (`Umar's brother) embraced Islam.