Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(They have taken as lords beside Allah) i.e. they obeyed them in acts of disobedience (their rabbis) the men of knowledge among the Jews (and their monks) who reside in monasteries (and the Messiah son of Mary) and they have taken the Messiah son of Mary as lord, (when they were bidden) in all Scriptures (to worship) to confess the divine Oneness of (only One God. There is no god save Him. Be He glorified from all that they ascribe as partner (unto Him)!) Allah exalts Himself above all that which they ascribe to Him.
They have taken their rabbis, the scholars among the Jews, and their monks, the devout among the Christians, as lords beside God — following them in making lawful what God has made unlawful and making unlawful what He has made lawful — and the Messiah, son of Mary, when they were not commanded, in the Torah and the Gospel, except to worship One God: there is no god except Him; glory be to Him, as an affirmation of His transcendence [high], above what they associate [with Him].
Fighting the Jews and Christians is legislated because They are Idolators and Disbelievers
Allah the Exalted encourages the believers to fight the polytheists, disbelieving Jews and Christians, who uttered this terrible statement and utter lies against Allah, the Exalted. As for the Jews, they claimed that `Uzayr was the son of God, Allah is free of what they attribute to Him. As for the misguidance of Christians over `Isa, it is obvious. This is why Allah declared both groups to be liars,
ذلِكَ قَوْلُهُم بِأَفْوَهِهِمْ
(That is their saying with their mouths), but they have no proof that supports their claim, other than lies and fabrications,
قَوْلَ الَّذِينَ كَفَرُواْ مِن قَبْلُ
(the saying of those who disbelieved aforetime.) They imitate the previous nations who fell into misguidance just as Jews and Christians did,
(may Allah fight them), Ibn `Abbas said, "May Allah curse them.''
(how they are deluded away from the truth!) how they deviate from truth, when it is apparent, exchanging it for misguidance. Allah said next,
(They took their rabbis and their monks to be their lords besides Allah, and the Messiah, son of Maryam) 9:31. Imam Ahmad, At-Tirmidhi and Ibn Jarir At-Tabari recorded a Hadith via several chains of narration, from `Adi bin Hatim, may Allah be pleased with him, who became Christian during the time of Jahiliyyah. When the call of the Messenger of Allah reached his area, `Adi ran away to Ash-Sham, and his sister and several of his people were captured. The Messenger of Allah freed his sister and gave her gifts. So she went to her brother and encouraged him to become Muslim and to go to the Messenger of Allah. `Adi, who was one of the chiefs of his people (the tribe of Tai') and whose father, Hatim At-Ta'i, was known for his generosity, went to Al-Madinah. When the people announced his arrival, `Adi went to the Messenger of Allah wearing a silver cross around his neck. The Messenger of Allah recited this Ayah;
(Yes they did. They (rabbis and monks) prohibited the allowed for them (Christians and Jews) and allowed the prohibited, and they obeyed them. This is how they worshipped them.) The Messenger of Allah said to `Adi,
(O `Adi what do you say Did you run away (to Ash-Sham) so that 'Allahu Akbar' (Allah is the Great) is not pronounced Do you know of anything greater than Allah What made you run away Did you run away so that `La ilaha illallah' is not pronounced Do you know of any deity worthy of worship except Allah)
The Messenger invited `Adi to embrace Islam, and he embraced Islam and pronounced the Testimony of Truth. The face of the Messenger of Allah beamed with pleasure and he said to `Adi,
(They took their rabbis and their monks to be their lords besides Allah...) that the Christians and Jews obeyed their monks and rabbis in whatever they allowed or prohibited for them. This is why Allah said,
(while they were commanded to worship none but One God), Who, whatever He renders prohibited is the prohibited, whatever He allowed is the allowed, whatever He legislates, is to be the law followed, and whatever He decides is to be adhered to;
(None has the right to be worshipped but He. Hallowed be He above what they associate (with Him).) Meaning, exalted, sanctified, hallowed above partners, equals, aids, rivals or children, there is no deity or Lord worthy of worship except Him.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
Uzair (Ezra) lived during the period around 450 B.C. The Jews regarded him with great reverence as the revivalist of their Scriptures which had beat lost during their captivity in Babylon after the death of Prophet Solomon. So much so that they had lost all the knowledge of their Law, their traditions and of Hebrew, their national language. Then it was Ezra who re-wrote the Old Testament and revived the Law. That is why they used very exaggerated language in his reverence which misled some of the Jewish sects to make him 'the son of God'. The Qur'an, however, does not assert that all the Jews were unanimous in declaring Ezra as 'the son of God'. What it intends to say is that the perversion in the articles of faith of the Jews concerning Allah had degenerated to such an extent that there were some amongst them who considered Ezra as the son of God.
"Those who were involved in Kufr before them" were the Egyptians, the Greeks, the Romans, the Persians, etc. The Jews and the Christians were so influenced by their philosophies, their superstitions and fancies that they also invented erroneous creeds like theirs. (For details sec E.N. 101 of Al-Maidah).
"They have taken their scholars and monks as their Lords the Holy Prophet himself explained its true significance. According to a Tradition, when Hadrat `Adi bin Hatim, who was formerly a Christian, came to the Holy Prophet with the intention of understanding Islam, he asked several questions in order to remove his doubts. One of these was: "This verse accuses us of taking our scholars and monks as our lords. What is its real meaning, sir? For we do not take them as our fords."
As a reply to this, the Holy Prophet put him a counter-question: "Is it not a fact that you accept as unlawful what they declare to be unlawful, and lawful what they declare to be lawful?" 'Adi confessed, "Yes, sir, it is so." The Holy Prophet replied, "This amounts to making them your lords." Incidentally, this Tradition shows that those who themselves set limits to the lawful and the unlawful without the authority of Allah's Book, assume for themselves the rank of Godhead, and those who acknowledge their right of making laws take them as their Lords.
It should be noted that they have been charged with (a) attributing sons to Allah, and (b) giving the right of making laws to others than Allah. These are to prove that their claim, that they believed in Allah, is false, even though they should believe in his existence. But such a wrong conception of Allah makes their belief in Allah meaningless.
The Arabic word ad-din has been translated into 'ways'. For the word din, as has already been explained in E.N. 204, :Al-Baqarah, is used for the 'way of life' or the 'system of life', which is followed in obedience to the supreme authority.
Now let us try to understand the significance of this verse. The object of the Mission of the Messenger is to make the Guidance and the Right Way he has brought from Allah dominant over all the other ways and systems of life. In other words, the Messenger is not sent to allow Allah's Way to remain subordinate to other ways in order to enjoy concessions from them. He is sent by the Sovereign of the earth and the heavens to make His Way dominant over all other ways. And if a wrong way is at all allowed to remain on the earth, it should be tolerated only under its own protection by the payment of Jizyah under the limits conferred by the Divine System as in the cast of the system of life of the Zimmis who pay Jizyah.
These religious leaders are guilty of two sins. First, they devour the wealth of the common people by selling false decrees, and by taking bribes, gifts and presents on different pretexts. They invent religious regulations and rituals as tempt people to buy their salvations and fortunes in life from them and make deaths and marriages dependent on the payment of due `price' to these "monopolists" of Paradise. To add to this another sin, they debar the people from the Way of Allah by involving them into different sorts of deviations and by obstructing the way of every Righteous Mission with the obstacles of `learned' doubts and `pious' suspicions.