Sayyiduna Asmar bin Mudarris (may Allah be pleased with him) said: I came to the Prophet (peace and blessings be upon him) and pledged allegiance to him (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Whoever gets first to something that no Muslim has got to before him, it belongs to him." So the people went out running and drawing lines (on the ground).
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 810