Pīrūz Nahāvandi (the victorious) (Persian: پیروز نهاوندی) (or Piruzān) also known by Arabs as Abu-Lu'lu'ah al-Nahawandi was a Persian soldier who served under the commander Rostam Farrokhzad, but was captured in the Battle of al-Qādisiyyah in AD 636 when the Persians were defeated by the Arab-Muslim army of Caliph `Umar ibn al-Khattāb on the western bank of the Euphrates River. After he was brought to Arabia as a prisoner, he managed to assassinate Umar in the Hijri year 23 (644–645).
Not much is known about Pirūz, except that judging by his name, he was most likely born in Nahavand, Iran. He was either Zoroastrian or a convert to Islam. It is also reported that he remained a Zoroastrian, whilst other sources report he was a Christian.
Move to Medina
In addition to his advanced military skills, Pirūz was a skilled workman, a carpenter and artisan, and his owner allowed him to live in his own household in the Islamic capital of Medina (although according to Ibn Sa'd, Mughira ibn Shu'ba, his owner who was also the governor of Basra, had written to 'Umar from Kufa; and then 'Umar had given Mughira special permission to send Pirūz to Medina, since captives were not permitted to live in Medina.
Design of the vertical-axis windmill
Before becomming a slave to Calif Umar, Pīrūz Nahāvandi used to design and build wind mills. In the 9th. century AD., Pīrūz brought a complaint to Umar about the high tax charged from him by his master Mughirah. Umar wrote to Mughirah and inquired about the tax; Mughirah's reply was satisfactory, but Umar held that the tax charged from Abu Lulu was reasonable, owning the to his daily income. Umar then is reported to have asked Abu Lulu to design a windmill for him, in which Pīrūz replies, " By God, I will build this [wind]mill of which the World will talk".
Pirūz was the slave of al-Mughira ibn Shu'ba. Al-Mughira used to deduct four dirhams from Piruz’s wages every day. As a result of this, Piruz met Umar and said, “O Commander of the Faithful, al-Mughira is taking too much from me; ask him to reduce it”. Umar then said, “Fear Allah and be good to your master”. Umar intended to speak to al-Mughira and ask him to reduce it, but Pirūz became angry and said, “His justice extends to all of them except me”.
However, Umar, after questioning al-Mughira about how much his income was in proportion to the tax that was being demanded from him (according to Abu Huwayrith), told Pirūz that he was such a skilled workman that he was sure to make a good wages; there was no need to reduce his obligation to his owner. This did not satisfy Pirūz, and he sulked. There were Persian children slaves in Medina, seeing them, Pirouz would say, "You have been enslaved at such a tender age. This Umar sees eaten my heart; I shall take his heart out in return".
In the Hijri year 23, whilst Umar had just begun leading the Fajr (morning) prayer in Al-Masjid an-Nabawi, Pirouz had hidden the dagger in his robe, the grip of which was in the middle, and hid himself in a corner of the mosque. Shortly after Umar had begun the prayer, Pirūz leaped upon him and stabbed him six times (only three times, according to Ibn Sa'd), this was five times in the stomach and once in the navel which proved fatal (other reports also make a mention of being stabbed in the shoulder). Pirūz made his way out of the mosque, wounding thirteen men who tried to stand in his way  Six to nine of the men later died as a result of Pirouz's lethality.
After he stabbed Umar, he made his way out of the mosque. Sunni sources state that he killed himself when he was surrounded by Umar's companions by using the same blade he used for the assassination. Some Shias believe that he left Medina for Iran, he then died and was buried in Kashan, where his tomb is located.
According to some people believes, Pirouz Nahavandi's tomb is "located on the road from Kashan to Fins, constructed in an eleventh-century distinctive Persian-Khwarezmian dynastic architectural style, consisted of a courtyard, porch and conical dome decorated with turquoise coloured tiles, and painted ceilings. The original date of its construction is unknown, but in second-half of fourteenth century it was fully restored and a new tombstone was placed over his grave." 
Controversy was caused recently when, in 2010, the International Union for Muslim Scholars called for the tomb to be destroyed, a request which was not well received by some Iranians, having been perceived as a specifically anti-Iranian act. The tomb is used as police head office.
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- Mohammad-Ali E. (28 June 2007), CAIS NEWS: Tomb of Firuzan (Abu-lolo) in Kashan to be Destroyed More than one of