مُّطَهَّرَةً  (purified): Purified from the wrongness and falsehood.

This verse explains the (clear evidence). A Messenger needs a sign, so that no one can say that he is a messenger from Allah (swt) without an evidence, a miracle or an endorsement from Allah (swt). He must attest his words by a miracle that proves that he is a messenger from Allah (swt).

The miracle, as we know, is the abnormal thing that does not subject to the laws and norms to prove its truthfulness from Allah (swt). All Prophets came with miracles (the stick of Moses, Noah’s ark, the coolness of fire …). However, our Prophet (saws) came with the Holy Qur’an.

There are some scholars who interpret the word مُنفَكِّينَ (to be parted) as finished with and turning from their disbelief. Then the (clear evidence) would be the Messenger of Allah (saw); because He comes with true evidence, inspired by Allah (swt), and through him the truth is recognized from the falsehood.

Others have said that مُنفَكِّينَ (to be parted) means departing from the worldly life, and leaving it. So, (the clear evidence) would be the torment that will affect them openly. Consequently, this verse (A Messenger from Allah, reciting purified scriptures) is, in this sense, starts new speech.

It is the mission of the Messenger, whom Allah (swt) sent, to recite to us what was revealed to him of the Book of Allah (swt). Allah (swt) says:

  ﴾كَمَا أَرْسَلْنَا فِيكُمْ رَسُولًا مِّنكُمْ يَتْلُو عَلَيْكُمْ آيَاتِنَا وَيُزَكِّيكُمْ وَيُعَلِّمُكُمُ الْكِتَابَ وَالْحِكْمَةَ وَيُعَلِّمُكُم مَّا لَمْ تَكُونُوا تَعْلَمُونَ﴿

(Just as We have sent among you a messenger from yourselves reciting to you Our verses and purifying you and teaching you the Book and wisdom and teaching you that which you did not know.)
(Al-Baqarah:151)

 ﴾لَقَدْ مَنَّ اللَّهُ عَلَى الْمُؤْمِنِينَ إِذْ بَعَثَ فِيهِمْ رَسُولًا مِّنْ أَنفُسِهِمْ يَتْلُو عَلَيْهِمْ آيَاتِهِ وَيُزَكِّيهِمْ وَيُعَلِّمُهُمُ الْكِتَابَ وَالْحِكْمَةَ وَإِن كَانُوا مِن قَبْلُ لَفِي ضَلَالٍ مُّبِينٍ﴿

(Certainly did Allah confer [great] favor upon the believers when He sent among them a Messenger from themselves, reciting to them His verses and purifying them and teaching them the Book and wisdom, although they had been before in manifest error.)
(Ali-Imran:164)

Thus, the Messenger (saws) came to recite the verses of the Noble Qur’an. He came with readable verses; to draw people’s attention to the visible signs in the universe, which Allah (swt) created.

يَتْلُو (reciting) the difference between reciting and teaching:

Recitation of the Holy Qur’an is reading the Holy Qur’an slowly and with understanding to comprehend the verses, it does not mean teaching, whereas, teaching the Holy Qur’an means reciting and teaching it, by this one can understand the meanings and apply them.

صُحُفًا  (scriptures): Allah (swt) describes them as scriptures, as He (swt) describes what was revealed to Moses (pbuh):

  ﴾أمْ لَمْ يُنَبَّأْ بِمَا فِي صُحُفِ موسى﴿

(Or has he not been informed of what was in the scriptures of Moses.) (An-Najm: 36)

Sheeth Idrees (pbut) also had scriptures:

 ﴾أوَلَمْ تَأْتِهِم بَيِّنَةُ مَا فِي الصُّحُفِ الْأُولَى ﴿

(Has there not come to them evidence of what was in the former scriptures?) (Taha: 36)

And Allah (swt) has told us about Ibrahim:

﴾ إنَّ هَٰذَا لَفِي الصُّحُفِ الْأُولَىٰ %  صُحُفِ إِبْرَاهِيمَ وَمُوسَىٰ ﴿

(Indeed, this is in the former scriptures, % The scriptures of Abraham and Moses) (Al-A‘laa: 18-19)

The difference between the scriptures of Abraham (pbuh), Moses (pbuh), and the scriptures of our Prophet (saws) is that the scriptures of them (pbut) are not their miracles. The miracle of Moses (pbuh) was the staff, and the miracle of Abraham (pbuh) was the coolness and safety of the fire upon him, whereas, the scripture revealed to our Prophet (saws); the Holy Qur’an, is the certain miracle of him (saws), verified to be an everlasting miracle over all ages

Scriptures is a plural; Thus, the meaning is to recite what is included in the scriptures.

مُّطَهَّرَةً   (purified): It is purified from any ugly words that may be mentioned about. The Qur’an is always being mentioned by the best words, and is praised by the best praise. It is purified because it is purified in the preserved tablet, as Allah (swt) says:

﴾ فَمَن شَاءَ ذَكَرَهُ %  فِي صُحُفٍ مُّكَرَّمَةٍ % مَّرْفُوعَةٍ مُّطَهَّرَةٍ ٰ﴿

(So whoever wills may remember it. % [It is recorded] in honored sheets, % Exalted and purified) (Abasa: 12-14)

That is, it is high in status, and purified from impurity, and from any distortion.