Sahih Bukhari Volume 9, Book 91, Hadith Number 366.

Narrated By Jabir bin Abdullah : On the day of (the battle of) the Trench, the Prophet called the people (to bring news about the enemy). Az-Zubair responded to his call. He called them again and Az-Zubair responded to his call again; then he called them for the third time and again Az-Zubair responded to his call whereupon the Prophet said, “Every prophet has his Hawairi (helper), and Az-Zubair is my Hawari.”