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Narrated Jabir bin 'Abdullah:
On the day of the battle of the Trench, the Prophet wanted somebody from amongst the people to volunteer to be a reconnoitre. Az-Zubair volunteered. He demanded the same again and Az-Zubair volunteered again. Then he repeated the same demand (thrice) and AzZubair volunteered once more. The Prophet then said, " Every prophet has a disciple and my disciple is Az-Zubair."