37:75As-Saaffaat

Allah's Messenger (ﷺ) said, "Noah will be called on the Day of Resurrection and he will say, 'Labbaik and Sa`daik, O my Lord!' Allah will say, 'Did you convey the Message?' Noah will say, 'Yes.' His nation will then be asked, 'Did he convey the Message to you?' They will say, 'No Warner came to us.' Then Allah will say (to Noah), 'Who will bear witness in your favor?' He will say, 'Muhammad and his followers. So they (i.e. Muslims) will testify that he conveyed the Message. And the Apostle (Muhammad) will be a witness over yourselves, and that is what is meant by the Statement of Allah "Thus We have made of you a just and the best nation that you may be witnesses over mankind and the Apostle (Muhammad) will be a witness over yourselves." (2.143)

Allah's Messenger (ﷺ) said, "Noah and his nation will come (on the Day of Resurrection and Allah will ask (Noah), "Did you convey (the Message)?' He will reply, 'Yes, O my Lord!' Then Allah will ask Noah's nation, 'Did Noah convey My Message to you?' They will reply, 'No, no prophet came to us.' Then Allah will ask Noah, 'Who will stand a witness for you?' He will reply, 'Muhammad and his followers (will stand witness for me).' So, I and my followers will stand as witnesses for him (that he conveyed Allah's Message)." That is, (the interpretation) of the Statement of Allah: "Thus we have made you a just and the best nation that you might be witnesses Over mankind .." (2.143)

On the day of (the battle of) the Trench, the Prophet (ﷺ) 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."

When the Prophet (ﷺ) called the people (Sadqa, a sub-narrator, said, 'Most likely that happened on the day of Al-Khandaq) Az-Zubair responded to the call (i.e. to act as a scout). The Prophet) called the people again and Az-Zubair responded to the call. The Prophet (ﷺ) then said, "Every prophet had a disciple and my disciple is Zubair bin Al-`Awwam."