Language:
كتاب الأدب
78  
Good Manners and Form (Al-Adab)
(9)
Chapter: To be good to one's brother who is a Mushrik
(9)
باب صِلَةِ الأَخِ الْمُشْرِكِ
Sahih al-Bukhari 5981

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.

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ مُسْلِمٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ دِينَارٍ، قَالَ سَمِعْتُ ابْنَ عُمَرَ ـ رضى الله عنهما ـ يَقُولُ رَأَى عُمَرُ حُلَّةَ سِيَرَاءَ تُبَاعُ فَقَالَ يَا رَسُولَ اللَّهِ ابْتَعْ هَذِهِ، وَالْبَسْهَا يَوْمَ الْجُمُعَةِ، وَإِذَا جَاءَكَ الْوُفُودُ‏.‏ قَالَ ‏"‏ إِنَّمَا يَلْبَسُ هَذِهِ مَنْ لاَ خَلاَقَ لَهُ ‏"‏‏.‏ فَأُتِيَ النَّبِيُّ صلى الله عليه وسلم مِنْهَا بِحُلَلٍ، فَأَرْسَلَ إِلَى عُمَرَ بِحُلَّةٍ فَقَالَ كَيْفَ أَلْبَسُهَا وَقَدْ قُلْتَ فِيهَا مَا قُلْتَ قَالَ ‏"‏ إِنِّي لَمْ أُعْطِكَهَا لِتَلْبَسَهَا، وَلَكِنْ تَبِيعُهَا أَوْ تَكْسُوهَا ‏"‏‏.‏ فَأَرْسَلَ بِهَا عُمَرُ إِلَى أَخٍ لَهُ مِنْ أَهْلِ مَكَّةَ قَبْلَ أَنْ يُسْلِمَ‏.‏
Reference : Sahih al-Bukhari 5981
In-book reference : Book 78, Hadith 12
USC-MSA web (English) reference : Vol. 8, Book 73, Hadith 11
  (deprecated numbering scheme)