Bukhari

Hadith Commentary:
What happened was that during the caliphate of Umar (radi Allahu anhu), the army of Islam marched towards Iran.
When they reached Qadisiyyah, Yazdegerd, the king of Iran, sent a large army to confront them.
This battle took place in 14 AH, in which the Muslims suffered considerable losses; Islamic heroes such as Tulayhah al-Asadi, Amr ibn Ma'dikarib, and Dhirar ibn Khattab were martyred.
Later, Allah the Exalted sent a fierce wind upon the disbelievers.
Their camps and tents were all uprooted; from the other side, the Muslims launched an attack, and the enemy fled. Their renowned champion, Rustam Thani, was killed, and the Muslim army pursued them all the way to Madain. There, the chief of the city, Hormuzan, was besieged; eventually, he sought amnesty and gladly embraced Islam.
Abu Musa al-Ash'ari (radi Allahu anhu), who was the commander of the army, sent him to Umar (radi Allahu anhu).
Umar (radi Allahu anhu) honored him, and finding him intelligent and prudent, made him a special advisor. Thus, Hormuzan gave sound counsel regarding Kisra.
Although he (Kisra) was the king of Rome, at that time Kisra's status was higher than all other kings; his downfall became the cause of the decline of both Iran and Rome. The commander of Kisra's army was a leader named Dhu al-Janahayn, who fell from his mule and his abdomen burst open.
After a fierce battle, the disbelievers were defeated; further details will follow.

Hadith Commentary:
➊
The fact is that during the caliphate of Umar radi Allahu anhu, the army of Islam marched towards Persia.
When they reached Qadisiyyah, the king of Persia, Yazdegerd, sent a formidable army to confront the Muslims, which caused considerable losses to the Muslims.
Islamic heroes such as Tulayhah Asadi, Amr ibn Ma'dikarib, and Dhirar ibn Khattab were martyred in this battle.
After this, Allah, the Exalted, sent a fierce wind that uprooted the tents of the disbelievers.
From the other side, the Muslims launched an attack.
They fled, and in this chaos, their renowned champion Rustam Thani was killed.
The mujahideen pursued them all the way to Madain.
There, their chief Hormuzan fortified himself in a citadel.
Eventually, he sought amnesty and happily embraced Islam.
Abu Musa Ash'ari radi Allahu anhu, who was the commander of the Islamic army, sent Hormuzan to Umar radi Allahu anhu.
Umar radi Allahu anhu honored him.
Finding him to be a man of insight and intelligence, he made him his special advisor. Thus, Hormuzan gave correct advice regarding Kisra, which is mentioned in the hadith under discussion.
(: ‘Umdat al-Qari: 508/10)

➋
When Mughirah ibn Shu’bah radi Allahu anhu saw that the enemy army was chained together with iron chains so that they could not flee, he wanted to attack them quickly so that they would not have the opportunity to prepare.
Nu’man radi Allahu anhu said:
“Indeed, you possess many virtues, but I will not act hastily. Rather, I will follow the Sunnah of the Messenger of Allah sallallahu alayhi wa sallam and wait for the sun to decline after the winds have blown, so that by following this, we may be granted success.”

➌
In this hadith, the mention of jizyah (tax on non-Muslims) occurs, and likewise, Nu’man ibn Muqarrin radi Allahu anhu delayed the attack on the enemy until the winds of victory blew and the sun declined.
This delay is a form of muwada’ah (truce), because there was a possibility of reconciliation in it.

➍
This hadith also indicates the importance of mutual consultation, and it is also understood that a person of higher rank can take advice from someone of lower status.
(: ‘Umdat al-Qari: 508/10)

➎
The wisdom behind imposing jizyah on non-Muslims is that it gives them an opportunity to reflect, and the humiliation of jizyah may incline them to accept Islam. Furthermore, by mingling with the Muslims, they will experience the virtues of Islam.
(: Fath al-Bari: 311/6)