4:171
يَٰٓأَهْلَ ٱلْكِتَٰبِ لَا تَغْلُوا۟ فِى دِينِكُمْ وَلَا تَقُولُوا۟ عَلَى ٱللَّهِ إِلَّا ٱلْحَقَّ ۚ إِنَّمَا ٱلْمَسِيحُ عِيسَى ٱبْنُ مَرْيَمَ رَسُولُ ٱللَّهِ وَكَلِمَتُهُۥٓ أَلْقَىٰهَآ إِلَىٰ مَرْيَمَ وَرُوحٌۭ مِّنْهُ ۖ فَـَٔامِنُوا۟ بِٱللَّهِ وَرُسُلِهِۦ ۖ وَلَا تَقُولُوا۟ ثَلَٰثَةٌ ۚ ٱنتَهُوا۟ خَيْرًۭا لَّكُمْ ۚ إِنَّمَا ٱللَّهُ إِلَٰهٌۭ وَٰحِدٌۭ ۖ سُبْحَٰنَهُۥٓ أَن يَكُونَ لَهُۥ وَلَدٌۭ ۘ لَّهُۥ مَا فِى ٱلسَّمَٰوَٰتِ وَمَا فِى ٱلْأَرْضِ ۗ وَكَفَىٰ بِٱللَّهِ وَكِيلًۭا
O People of the Scripture, do not commit excess in your religion or say about Allah except the truth. The Messiah, Jesus, the son of Mary, was but a messenger of Allah and His word which He directed to Mary and a soul [created at a command] from Him. So believe in Allah and His messengers. And do not say, "Three"; desist - it is better for you. Indeed, Allah is but one God. Exalted is He above having a son. To Him belongs whatever is in the heavens and whatever is on the earth. And sufficient is Allah as Disposer of affairs.
Translation · Saheeh International
Tafsir
Ibn Kathīr (abridged)
Prohibiting the People of the Book From Going to Extremes in Religion
Allah forbids the People of the Scriptures from going to extremes in religion, which is a common trait of theirs, especially among the Christians. The Christians exaggerated over `Isa until they elevated him above the grade that Allah gave him. They elevated him from the rank of prophethood to being a god, whom they worshipped just as they worshipped Allah. They exaggerated even more in the case of those who they claim were his followers, claiming that they were inspired, thus following every word they uttered whether true or false, be it guidance or misguidance, truth or lies. This is why Allah said,
اتَّخَذُواْ أَحْبَـرَهُمْ وَرُهْبَـنَهُمْ أَرْبَاباً مِّن دُونِ اللَّهِ
(They took their rabbis and their monks to be their lords besides Allah.) Imam Ahmad recorded that Ibn `Abbas said that `Umar said that the Messenger of Allah ﷺ said,
«لَا تُطْرُونِي كَمَا أَطْرَتِ النَّصَارَىِ عِيسَى ابْنَ مَرْيَمَ. فَإِنَّمَا أَنَا عَبْدٌفَقُولُوا: عَبْدُاللهِ وَرَسُولُه»
(Do not unduly praise me like the Christians exaggerated over `Isa, son of Maryam. Verily, I am only a servant, so say, `Allah's servant and His Messenger.') This is the wording of Al-Bukhari. Imam Ahmad recorded that Anas bin Malik said that a man once said, "O Muhammad! You are our master and the son of our master, our most righteous person and the son of our most righteous person..." The Messenger of Allah ﷺ said,