On the occasion of the Battle of Ahzaab, also known as the Battle of Khandaq (the Battle of the Trench), the Muslims received the information that the Banu Quraizah had broken their pledge of allegiance to Rasulullah (sallallahu ‘alaihi wasallam) and had joined the enemy. In order to verify the information, Rasulullah (sallallahu ‘alaihi wasallam) asked the Sahaabah (radhiyallahu ‘anhum), “Who will bring me information of these people (the Banu Quraizah)?” Hazrat Zubair (radhiyallahu ‘anhu) instantly responded by volunteering to go as a spy and bring information of the Banu Quraizah to Rasulullah (sallallahu ‘alaihi wasallam).
After some time, Rasulullah (sallallahu ‘alaihi wasallam) again asked, “Who will bring me information of these people (the Banu Quraizah)?” Once again, Hazrat Zubair (radhiyallahu ‘anhu) volunteered to go. Finally, Rasulullah (sallallahu ‘alaihi wasallam) asked for a third time, “Who will bring me information of these people (the Banu Quraizah)?” On this occasion as well, Hazrat Zubair (radhiyallahu ‘anhu) volunteered to go. It was on this occasion that Rasulullah (sallallahu ‘alaihi wasallam) was overjoyed and pleased with Hazrat Zubair (radhiyallahu ‘anhu) and mentioned, “Indeed every Nabi had a special helper, and my special helper is Hazrat Zubair bin ‘Awwaam (radhiyallahu ‘anhu).”
(Siyar A’laam min Nubalaa 3/30, Saheeh Bukhaari #3719, Saheeh Muslim #2415, Sunan Tirmizi #3745, Fat-hul Baari 6/63, 7/100)