(47) بَابُ إِذَا اشْتَرَى شَيْئًا فَوَهَبَ مِنْ سَاعَتِهِ قَبْلَ أَنْ يَتَفَرَّقَا وَلَمْ يُنْكِرِ الْبَائِعُ عَلَى الْمُشْتَرِي، أَوِ اشْتَرَى عَبْدًا فَأَعْتَقَهُ
Narrated Ibn 'Umar (ra) :
We were accompanying the Prophet (ﷺ) on a journey and I was riding an unmanageable camel belonging to 'Umar (ra), and I could not bring it under my control. So, it used to go ahead of the party and 'Umar would check it and force it to retreat, and again it went ahead and again 'Umar forced it to retreat. The Prophet (ﷺ) asked 'Umar to sell that camel to him. 'Umar replied, "It is for you O Allah's Messenger !" Allah's Messenger (ﷺ) told 'Umar to sell that camel to him (not to give it as gift). So, 'Umar sold it to Allah's Messenger (ﷺ). Then the Prophet (ﷺ) said to 'Abdullah bin 'Umar "This camel is for you O 'Abdullah (as a present) and you could do with it whatever you like."
Reference: Sahih al-Bukhari 2115
In-book reference: Book 34, Hadith 68
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 34, Hadith 328