Abu Raja' (may Allah have mercy on him) narrates from Sayyiduna Imran (may Allah be pleased with him) that he was with the Prophet (peace and blessings be upon him), and they travelled through the night until, when they were close to dawn, the Messenger of Allah (peace and blessings be upon him) halted to rest, and sleep overcame them until the sun had risen high. The first to wake from his sleep was Abu Bakr (may Allah be pleased with him). It was the way of the Messenger of Allah (peace and blessings be upon him) that no one would wake him (peace and blessings be upon him) from his sleep until the Prophet (peace and blessings be upon him) woke up by himself. Then Umar (may Allah be pleased with him) woke up, and at his (peace and blessings be upon him) head he began to say the takbir and raise his voice, until the Prophet (peace and blessings be upon him) woke up. When he (peace and blessings be upon him) saw that the sun had risen, he said: "Set off." He (peace and blessings be upon him) travelled with us until the sun became bright, then he dismounted and led us in prayer. A man kept apart and did not pray with us. When he (peace and blessings be upon him) finished the prayer, he said: "O so-and-so! What kept you from praying with us?" He said: O Messenger of Allah, I have become in need of a ritual bath (ghusl). So he (peace and blessings be upon him) ordered him to perform tayammum with clean earth, and then he prayed. The Messenger of Allah (peace and blessings be upon him) sent me ahead of him with a few riders to look for water, and we were extremely thirsty. While we were travelling, we came upon a woman sitting with her legs hanging down between two water-skins. We asked her: Where is the water? She said: Far away, far away, there is no water. We said: How far is it between you and the water? She said: A day and a night. We said: Come along to the Messenger of Allah (peace and blessings be upon him). She said: Who is the Messenger of Allah (peace and blessings be upon him)? We did not leave her any choice in the matter until we brought her before the Messenger of Allah (peace and blessings be upon him). Then we opened the mouths of the two water-skins, and we drank, forty thirsty men, until we had quenched our thirst, and we filled every water-skin and container we had with us. Then he (peace and blessings be upon him) said to us: "Bring whatever you have." So we gathered pieces of bread and dates for her until we made a bundle for her. Then he said: "Go and feed this to your family, and know that we have not taken anything from your water." When she came to her family, she said: We met the greatest sorcerer, or he is indeed a prophet as they claim. Through that woman, Allah guided that tribe: she accepted Islam, and they all accepted Islam.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15380