A brief biography of al-Hajjaaj ibn Yoosuf ath-Thaqafi
Question

Was al-Hajjaaj ibn Yoosuf ath-Thaqafi a Muslim? In what ways did he benefit and harm the believers?
Praise be to Allah.al-Hajjaaj ibn Yoosuf ath-Thaqafi was the governor of Iraq for the caliph ‘Abd al-Malik ibn Marwaan. He was known for oppression and bloodshed, showing disrespect to the early generations [the Sahaabah and Taabi‘een] and transgressing all the sacred limits of Allah for the slightest reason. The historians and biographers are unanimously agreed that he was one of the worst oppressors and the quickest to shed to kill people unlawfully. He did not show respect to the Messenger of Allah (blessings and peace of Allah be upon him) in the way he treated his companions, and he showed no respect to the Prophet’s instructions to show kindness and respect to the scholars and people of virtue and righteousness among the followers of his companions. He was a vile Naasibi who hated ‘Ali ibn Abi Taalib (may Allah be pleased with him) and his family.
Ibn Katheer (may Allah have mercy on him) said:
He was a Naasibi who hated ‘Ali and his supporters so as to appease the family of Marwaan, namely Banu Umayyah. He was a stubborn tyrant, always ready to shed innocent blood for the slightest reason.
Some ugly and abhorrent words were narrated from him, the apparent meaning of which sounds like disbelief (kufr). If he had repented from that and given it up, that would have been counted in his favour, otherwise he is responsible for what he said. But there is the fear that these reports may have been inaccurate, with things added to what he said, because the Shi‘ah hated him intensely for many reasons, and they may have distorted some of his words and added to what they narrated from him some abhorrent and ugly words." (Al-Bidaayah wa’n-Nihaayah 9/153).
It was narrated from Asma’ bint Abi Bakr (may Allah be pleased with her) that she said to al-Hajjaaj: The Messenger of Allah (blessings and peace of Allah be upon him) told us that among Thaqeef there would be a liar and a shedder of blood. As for the liar, we have seen him; as for the shedder of blood, I do not think but that you are he.
The shedder of blood is the one who goes to extremes in killing people.
From an early age al-Hajjaaj was known to be intelligent, well-spoken and eloquent, and a hafiz of Qur’an. Some of the early generations said: al-Hajjaaj used to recite the entire Qur’an every night. Abu ‘Amr ibn al-‘Ala’ said: I have never seen anyone more eloquent [in Arabic] than him and al-Hasan al-Basri, but al-Hasan was more eloquent than him.
‘Uqbah ibn ‘Aamir said: I think that in terms of intelligence, people are close to one another, except al-Hajjaaj and Iyaas ibn Mu‘aawiyah, for their intelligence stood out in comparison to other people." (Al-Bidaayah wa’n-Nihaayah 9/138-139).
Ibn Katheer said:
It was narrated to us that he was a religious person with regard to keeping away from intoxicants. He recited Qur’an a great deal and avoided other sins. It was not known that he ever committed fornication; however, he would not hesitate to shed the blood of innocent people. Allah, may He be exalted, knows best what is true and how matters really were, what is hidden of such matters and what is concealed in people’s hearts.
The worst of his evil deeds that made people hate him and it is proven that he did it was shedding blood. That is sufficient to make him deserve punishment from Allah, may He be glorified and exalted. However, he was very keen to engage in jihad and conquer many lands. He was very generous and gave gifts to the people of the Qur’an; he would spend a great deal on the reciters of the Qur’an and when he died, he did not leave behind anything except three hundred dirhams, or so it was said." (Al-Bidaayah wa’n-Nihaayah  9/153).
He was a man of great chivalry, but he often hastened to use his sword unlawfully. He killed many people for the slightest reason  whom he had no right to kill, and when he got angry he would act on his anger (and wreak vengeance, punishing people) as if he were a king. " (Al-Bidaayah wa’n-Nihaayah 9/138).
He went to extremes in transgressing the limits and would hasten to do evil; he would bear grudges and was filled with envy.
It was narrated from ‘Aasim ibn Abi’n-Najood and al-A‘mash that they heard al-Hajjaaj say to the people: By Allah, if I ordered you to exit through this door and you exited through that door, it would become permissible for me to shed your blood. If I find anyone reciting Qur’an according to the recitation of Ibn Umm ‘Abd [‘Abdullah ibn Mas‘ood], I will strike his neck and erase it from  that Mus-haf, even if I have to use the rib of a pig.
Al-Asma‘i said: ‘Abd al-Malik said to al-Hajjaaj one day: There is no one but he knows his shortcomings, so tell me about your shortcomings. He said: Let me off, O Ameer al-Mu’mineen. But he insisted, so al-Hajjaaj said: I am very stubborn, and my heart is filled with grudges and envy. ‘Abd al-Malik said: Then you must be descended from Iblees!" (Al-Bidaayah wa’n-Nihaayah 9/149-153).
A number of leading scholars were of the view that he was a disbeliever (kaafir), although most of the scholars did not think that he was a disbeliever. Some of the Sahaabah, such as Anas and Ibn ‘Umar, prayed behind him, and if they had regarded him as a disbeliever, they would not have prayed behind him.
It was narrated that Qataadah said: It was said to Sa‘eed ibn Jubayr: Did you rebel against al-Hajjaaj? He said: By Allah, I did not rebel against him until he became a disbeliever.
Al-A‘mash said: They differed concerning al-Hajjaaj, so they asked Mujaahid and he said: Are you asking me about this disbelieving old man?
Al-Bidaayah wa’n-Nihaayah (9/157-156).
Ash-Sha‘bi said: al-Hajjaaj was a believer in taaghoot (falsehood), and a disbeliever in Allah the Almighty.
Al-Qaasim ibn Mukhaymarah said: al-Hajjaaj is undoing the knots of Islam.
It was narrated that ‘Aasim ibn Abi’n-Najood said: There is no sacred limit ordained by Allah, may He be exalted, but al-Hajjaaj transgressed it." (Taareekh Dimashq  12/185-188).
At-Tirmidhi narrated in his Sunan (2220) that Hishaam ibn Hassaan said: They counted how many people al-Hajjaaj captured then killed, and the number reached one hundred and twenty thousand.
‘Umar ibn ‘Abd al-‘Azeez said: If the nations were to compete in evildoing when al-Hajjaaj is part of our community, we would surpass them in evil because of his evil deeds. He was not good for the people’s affairs in this world or in the hereafter." (Taareekh Dimashq  12/185).
He was careless and heedless about prayer, and did not pray on time:
‘Umar ibn ‘Abd al-‘Azeez wrote to ‘Adiy ibn Artaat, saying: I have heard that you are following in the footsteps of al-Hajjaaj. Do not follow in his footsteps, for he used to offer the prayer after the time for it had ended and take people’s wealth unlawfully, and he was even more negligent with regard to other matters." ( Taareekh Dimashq 12/187).
Adh-Dhahabi (may Allah have mercy on him) said:
He was an oppressor, a tyrant, a Naasibi, an evil man and a shedder of blood.
He was very courageous, brave, devious, crafty, well-spoken and eloquent, and he had a great deal of respect for the Qur’an.
I have mentioned his bad conduct in at-Taareekh al-Kabeer, including his siege of Ibn az-Zubayr when he holed up at the Ka‘bah, how he launched projectiles at it with the catapult, and how he humiliated the residents of the Haramayn (the two holy cities of Makkah and Madinah); then his governorship of Iraq and the entire East (i.e., Persia) for twenty years; the rebellion of Ibn al-Ash‘ath against him; and his delaying of prayers until Allah eradicated him.
We revile him and do not love him; rather we hate him for the sake of Allah, for that is one of the strongest bonds of faith.
He did some good deeds, but they are like drops in the ocean of his evil deeds, and his ultimate fate is subject to the will of Allah.
He affirmed Allah’s oneness (Tawheed) in general, and there are other oppressive tyrants and governors of his ilk. End quote.
Siyar A‘laam an-Nubala’ (4/343).
To sum up, the man did a great deal of wrong and transgressed against the people, and he wronged himself a great deal.
He did some good deeds, but they are like drops in the ocean of his evil deeds. However, he strove hard in jihad, fought the enemies of Allah, conquered lands and spread Islam.
Allah, may He be exalted, will judge him. We condemn before Allah his oppression and transgression, and we declare our love and support for those of the Muslim leaders among the Sahaabah and Taabi‘een against whom he transgressed. We regard him as an enemy because of his mistreatment of them, and we leave his final judgement to Allah, may He be exalted.
It is better not to focus on him and worry about him. How good are the words narrated by Imam Ahmad (may Allah have mercy on him) in az-Zuhd (p. 332) from Bilaal ibn al-Mundhir, who said: A man said: If I do not ask ar-Rabee‘ ibn Khaytham today about what happened, I will never find out his view. I said: O Abu Yazeed, the son of Faatimah (peace be upon her) – meaning al-Husayn – was killed. He said: Inna Lillahi wa inna ilayhi raaji‘oon (Indeed we belong to Allah , and indeed to Him we will return), then he recited the verse (interpretation of the meaning): {Say, “O Allah , Creator of the heavens and the earth, Knower of the unseen and the witnessed, You will judge between your servants concerning that over which they used to differ”} [az-Zumar 39:46].
I said: What do you say? He said: What should I say? To Allah they will return and Allah will bring them to account.
And Allah knows best.
See: Wafiyyaat al-A‘yaan (2/29-46); Taareekh Dimashq (12/113-123); Taareekh al-Islam (5/310-316; 6/314-327).