Sayyiduna Abdullah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) and Abu Bakr (may Allah be pleased with him) came to me, having fled from the polytheists, while I was herding the goats of Ibn Abi Mu'ayt at Jiyad. He (peace and blessings be upon him) said: "O boy, do you have milk to give us to drink?" I said: "I am entrusted, and I am not the one to give you drink (that is, these goats are a trust; I cannot give you their milk)." He (peace and blessings be upon him) said: "Do you have a young goat that no male has yet mounted?" I said: "Yes," and I brought it to him. He (peace and blessings be upon him) passed his hand over the udder, and the udder filled with milk. Abu Bakr (may Allah be pleased with him) brought a hollowed-out stone, and he (peace and blessings be upon him) milked it, drank himself, and gave me and Abu Bakr (may Allah be pleased with him) to drink. Then he said to the udder: "Shrink," and it shrank.
After that I came to him (peace and blessings be upon him) and said: "O Messenger of Allah, teach me some of this speech, or of this Qur'an." He (peace and blessings be upon him) said: "You are a boy who is taught." So I took seventy surahs from the mouth of the Messenger of Allah (peace and blessings be upon him); no one disputes with me about them.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8423