Noaman heard about the Prophet's (pbuh) message and announced his decision
Noaman was member of the Al-Mazeena tribe that lived on the outskirts of Yathrib on the road that led out of the city to Makkah. He was first among those who embraced Islam on the invitation of Prophet Muhammad, peace be upon him. When he heard about the Prophet's message, he announced his decision to turn over to Islam and 10 of his brothers joined him the next morning. Another 400 youth, who were veteran fighters of the tribe, also joined the group soon after. This provided a tremendous boost to the neo-Muslim society and the occasion led to revelation of some verses of the Quran.
Prior to the Battle of Qadissiya which delivered Iran to the Islamic fold, a delegation of the Islamic government was sent to the emperor of Iran to invite him to Islam by Saad bin Abi Waqqas. Waqqas appointed Noaman as the leader who also acted as the chief spokesman of the Islamic government. Noaman told the emperor: "We invite you to Islam which we find a code of life superior to all others. It rescues you from all the evils. If you fashion the administration of your sultanate in accordance with Islam, we will not interfere in your affairs. If you accept Islam, we will leave the book of Allah with you in order that you deduce the commandments of Allah. But if you refuse, we will impose jizyah on you and you will be protected by us. If you refuse jizyah, you can consider yourselves on war with us".
The plainspeak by Noaman infuriated the Iranian emperor. He ridiculed them all and said, "I would have dealt sternly with you, had I not been bound by International convention to respect the rights of the ambassadors. He then ordered his men to expel the delegation out of the boundaries of the Iranian sultanate and asked them to leave them out of the frontiers in a situation in which a bag of soil is kept on the neck of the most respected of the members of the delegation. They were asked to identify this member. Asim bin Umar accepted to carry the bag. The emperor also warned them against the war and said he would bury them and their leader in the trenches of Qadissiya if they ever thought of war.
Not long after this incident, Muslims and the Iranians fought the war at Qadissiya. Trenches were indeed filled with bodies. But all these bodies belonged to Iranians.
But soon the Iranians came back to avenge their defeat and collected a huge army of 1.5 lakh people at Nahavand. Caliph Umar appointed Noaman to lead the Muslim armies. Noaman was a veteran warrior and was an extremely agile and swift marksman. On reaching the outskirts of Nahavand, Noaman dispatched a reconnaissance to inspect the Iranian preparations. The team found to its horror that all its horses had stopped in their track. It was soon discovered that the Iranians had laid nails on all the routes leading to Nahavand to block the entry of the infantry and the cavalry. Soon Noaman was informed about the unpredictable situation. Noaman ordered the entire Muslim army to set up fires all around them soon after dusk fell. He ordered them to pretend as if the Muslim army was on retreat and was depressed with the new situation. This, he imagined, would entice them into an attack which would require them to remove the nails themselves and proceed.
He was right in his guess. The fires were mistaken as a sign of retreat by the Muslim army. Iranians came to attack. The Noaman's army launched a powerful assault. Noaman himself had taken a convoy of his cavalry to another side. They all plunged headlong with a sudden thrust against the enemy. The Iranians were not ready for this push by the Muslims. They were taken by surprise, routed and chased and killed in large numbers. During the battle, Noaman's horse slipped on the blood and died. Noaman too died due to the fall. His brother who was nearby soon came to the spot, covered his body with a chador and himself took up the standard of the army.
The Muslims emerged victorious. As people came searching for their leader Noaman, his brother removed the chador to show them the body of Noaman. Noaman had fallen martyr but delivered the much needed victory.
(Abridged and translated by