Sunnan Abu Dawud Collection: ::Book Number 19:: Hadith # 3066
Narrated Abdullah ibn Umar: The Prophet (peace_be_upon_him) gave az-Zubayr the land as a fief up to the reach of his horse when he runs. He, therefore, made his horse run until it stopped. He then threw his flog. Thereupon he said: Give him (the land) up to the point where his flog has reached.