Ibn 'Abbas (May Allah be pleased with them) reported:
Messenger of Allah (ﷺ) came across a party of mounted men at Ar-Rauha and asked them, "Who are you?" They answered: "We are Muslims, and who are you?" He said, "I am the Messenger of Allah." A woman from among them lifted a boy up to him and asked: "Can this one go on Hajj?" He (ﷺ) said, "Yes, and you will have the reward."[Muslim].
Arabic/English book reference: Book 1, Hadith 179