It is narrated from Sayyiduna Ya'la (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said to a man: "Give me this camel as a gift, or sell it to me." He said: "It is yours, O Messenger of Allah." So he (peace and blessings be upon him) marked it with the brand of charity (sadaqah), then sent it on.
Hadith Referenceالمعجم الكبير للطبراني / باب الياء / 18898