Sahih Bukhari Volume 005, Book 057, Hadith Number 004.
Narated By Al-Bara : Abu Bakr bought a (camel) saddle from 'Azib for thirteen Dirhams. Abu Bakr said to 'Azib, "Tell Al-Bara' to carry the saddle for me." 'Azib said, "No, unless you relate to me what happened to you and Allah 's Apostle when you left Mecca while the pagans were in search of you." Abu Bakr said, "We left Mecca and we travel led continuously for that night and the following day till it was midday. I looked (around) searching for shade to take as shelter, and suddenly I came across a rock, and found a little shade there. So I cleaned the place and spread a bed for the Prophet in the shade and said to him, 'Lie down, O Allah's Apostle.' So the Prophet lay down and I went out, looking around to see if there was any person pursuing us. Suddenly I saw a shepherd driving his sheep towards the rock, seeking what we had already sought from it. I asked him, 'To whom do you belong, O boy?' He said, 'I belong to a man from Quraish.' He named the man and I recognized him. I asked him, 'Is there any milk with your sheep?' He said, 'Yes.' I said, 'Will you then milk (some) for us?' He said, 'Yes.' Then I asked him to tie the legs of one of the sheep and clean its udder, and then ordered him to clean his hands from dust. Then the shepherd cleaned his hands by striking his hands against one another. After doing so, he milked a small amount of milk. I used to keep for Allah's Apostle a leather water-container, the mouth of which was covered with a piece of cloth. I poured water on the milk container till its lower part was cold. Then I took the milk to the Prophet whom I found awake. I said to him, 'Drink, O Allah's Apostle.' So he drank till I became pleased. Then I said, 'It is time for us to move, O Allahs Apostle!' He said, 'Yes.' So we set out while the people (i.e. Quraish pagans) were searching for us, but none found us except Suraiqa bin Malik bin Jushum who was riding his horse. I said, 'These are our pursuers who have found us. O Allah's Apostle!' He said, 'Do not grieve, for Allah is with us."