Abu Dawud
Tributes, Spoils And Rulership
Book Number: 013 / Hadith Number: 3065
Narated By Asmar ibn Mudarris : I came to the Prophet (pbuh), and took the oath of allegiance to him. He said: If anyone reaches a water which has not been approached before by any Muslim, it belongs to him. The people, therefore, went out running and marking (on the land).