From Sahih Muslim (Hadith 4517):
Abu Sa'id al-Khudri reported:While we were with the Messenger of Allah (ﷺ) on a journey, a person came upon his mount and began to stare on the right and on the left, (it was at this moment) that Allah's Messenger (ﷺ) said: He who has an extra mount should give that to one who has no mount for him, and he who has surplus of provisions should give them to him who has no provisions, and he made mention of so many kinds of wealth until we were of the opinion that none of us has any right over the surplus
Reference: Muslim 4517