During the time of ‘Umar ibn al-Khattab (may Allah be pleased with him), Amr ibn al-‘As was in Egypt, and requested fighters. ‘Umar (radiallahu ‘an) sent a letter saying “I’ll send you 8000 fighters.” He sent 4000 fighters. ‘Amr ibn al-‘As (radiallahu ‘an) replied and said (to the meaning of) “you said you sent 8000 and you sent 4000,” and ‘Umar (radiallahu ‘an) said “I sent 4000, and at the head of each thousand is a man worth 1000 himself.
Az-Zubayr (radiallahu ‘an) was one of those men worth 1000.
In the battle of Yarmuk, where the Muslims fought 100 000+ Roman soldiers, Az-Zubayr fought the army himself. This incident is in Sahih Bukhari.
To encourage the Muslims, he stood in front of them and said “who will pledge to go and fight to the death?” so a group stepped forward, and they’d go and fight.
They’d all be martyred, may Allah be pleased with them all. Then he’d come back and say the same thing again–“who will pledge to fight to the death?” so a smaller group stepped forward, and they’d go and fight, and only he would return.
This happened a few times. Although his goal was to uplift spirits, the Muslimeen became dejected–like “anyone who goes with him will die”.
So when nobody stepped forward, he turned to his son Abdullah (may Allah be pleased with him) and said “Ok, if nobody’s going, let’s you and me go. And fight the entire army. By ourselves.” (Abdullah was about 13–so this would be like his eight-grade field-trip …)
So Abdullah (radiallahu ‘an) led the horse, and they went into the Roman army and fought.
They took on the entire army themselves and cut directly into the army, like through the middle. Az-Zubayr (radiallahu ‘an) fought Roman warriors in 360 degrees.
They cut through, into the middlle–the most intense part of the army–then out the back.
And then to get back to the Muslims, instead of going around, they went back through the middle again, fought the Romans 360 degrees, all the way through the army, back to where they started from.
A great deal of time had passed–so much so that the Muslims thought they were dead. But then, they returned.
One of the companions (may Allah be pleased with them) said “ma awwan ar-Room” (how weak the Romans). And then the Muslims fought and defeated the Roman army.
Muhammad Alshareef. Lecture. AlMaghrib. Conquest: History of the Khulafa. University of Toronto, Toronto. November 2005.