كتاب الهبات
24  
The Book of Gifts
(1)
Chapter: It Is Disliked For A Man To Buy What He Gave In Charity From The One To Whom He Gave It
(1)
باب كَرَاهَةِ شِرَاءِ الإِنْسَانِ مَا تَصَدَّقَ بِهِ مِمَّنْ تَصَدَّقَ عَلَيْهِ ‏‏
Sahih Muslim 1620 b

This hadith has been narrated on the authority of Malik b. Anas with the same chain of transmitters but with this addition:

" Don't buy that even if he gives you for one dirham."
وَحَدَّثَنِيهِ زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا عَبْدُ الرَّحْمَنِ، - يَعْنِي ابْنَ مَهْدِيٍّ - عَنْ مَالِكِ، بْنِ أَنَسٍ بِهَذَا الإِسْنَادِ وَزَادَ ‏ "‏ لاَ تَبْتَعْهُ وَإِنْ أَعْطَاكَهُ بِدِرْهَمٍ ‏"‏ ‏.‏
Reference : Sahih Muslim 1620b
In-book reference : Book 24, Hadith 2
USC-MSA web (English) reference : Book 12, Hadith 3949
  (deprecated numbering scheme)