قُلْ فَأْتُوا بِكِتَابٍ مِنْ عِنْدِ اللَّهِ هُوَ أَهْدَى مِنْهُمَا أَتَّبِعْهُ إِنْ كُنْتُمْ صَادِقِينَ ﴿۴۹﴾ فَإِنْ لَمْ يَسْتَجِيبُوا لَكَ فَاعْلَمْ أَنَّمَا يَتَّبِعُونَ أَهْوَاءَهُمْ وَمَنْ أَضَلُّ مِمَّنِ اتَّبَعَ هَوَاهُ بِغَيْرِ هُدًى مِنَ اللَّهِ إِنَّ اللَّهَ لَا يَهْدِي الْقَوْمَ الظَّالِمِينَ ﴿۵۰﴾ وَلَقَدْ وَصَّلْنَا لَهُمُ الْقَوْلَ لَعَلَّهُمْ يَتَذَكَّرُونَ ﴿۵۱﴾ الَّذِينَ آتَيْنَاهُمُ الْكِتَابَ مِنْ قَبْلِهِ هُمْ بِهِ يُؤْمِنُونَ ﴿۵۲﴾ وَإِذَا يُتْلَى عَلَيْهِمْ قَالُوا آمَنَّا بِهِ إِنَّهُ الْحَقُّ مِنْ رَبِّنَا إِنَّا كُنَّا مِنْ قَبْلِهِ مُسْلِمِينَ ﴿۵۳﴾

﴾49﴿ Qul faatoo bi Kitaabim min 'indil laahi huwa ahdaa minhu maaa attabi'hu in kuntum saadiqeen
﴾50﴿ Fa il lam yastajeeboo laka fa'lam annamaa yattabi'oona ahwaaa'ahum; wa man adallu mimmanit taba'a hawaahu bighari hudam minal laah; innal laaha laa yahdil qawmaz zaalimeen
﴾51﴿ Wa laqad wassalnaa lahumul qawla la'allahum yatazakkaroon
﴾52﴿ Allazeena aatainaahu mul Kitaaba min qablihee hum bihee yu'minoon
﴾53﴿ Wa izaa yutlaa 'alaihim qaaloo aamannaa biheee innahul haqqu mir rabbinaaa innaa kunnaa min qablihee muslimeen

﴾49﴿ So bring a book from Allah that is a better guide than these two, so I may follow it, if you are truthful
﴾50﴿ So if they do not accept your words, then know that they are merely following their own desires. And who is more astray than the one who follows his desires without guidance from Allah? Indeed, Allah does not grant success to a wrongdoing people
﴾51﴿ And indeed, We have conveyed the word to them continuously so that they may take heed
﴾52﴿ Those to whom We gave the Book before the Quran, they believe in it
﴾53﴿ And when it is recited to them, they say, We have believed in it. Indeed, it is the truth from our Lord. Indeed, we were Muslims (submitting to Allah) even before this

[49] This is the response to their statement “Sih'rāni taẓāharā” — meaning, they deny both the Qur’an and the Torah. So the challenge is given to them: Then bring a book better in guidance than these two, in which shirk (associating partners with Allah) is permitted — on the condition that it is truly from Allah the Exalted.
[50] This expresses their inability to bring forth a book supporting their shirk, and the statement following it begins with “fa” (so) as a logical consequence — meaning: when one has no divine proof, it necessarily follows that they are merely following their desires.
And following desires leads to misguidance and injustice.
[51] This is a refutation of those who follow their desires.
(Waṣṣalnā lahumu) — meaning, We have sent revelation to them continuously through successive Messengers, in order to remove the excuse of the people.
Or, the intended meaning of “the word” (al-qawl) is the content of the Qur’an — and that refers to its promises and warnings, claims, proofs, stories, parables, and so on — all of which We have conveyed and explained one after another.
Thus, this is an encouragement toward the Qur’an.
[52] This is a transmitted (naqlī) proof from the scholars among the People of the Book, and ten of their qualities are mentioned.
In this verse, the first of their qualities is mentioned: the pronoun bihi refers to the Book — meaning, they have faith in their own scripture.
[53] In this verse, two qualities are mentioned:
1. Faith in the Qur’an
2. Acceptance of Islam before the Qur’an was revealed
Here, the pronoun bihi refers to the Qur’an. From this, it becomes clear that even previous peoples were also called Muslims — those among them who had brought true faith.