One of the beauties of the Qur’an is that a person can connect the words in a verse and; with each way the words will be put together  a person will get a different shade of meaning; and one of the mysteries of this Book is that one meaning will not contradict with the original meaning.  For example, in the first verse in Surah Kahf.  Allah says;

‘Praise be to Allah, Who hath sent to His servant the Book, and hath allowed therein no Crookedness’.  (18:1)

The first part of the verse is clear, i.e. ‘Praise be to Allah, Who hath sent to His servant the Book’.  As we all know Allah is The One Who revealed the Glorious Qur’an to His slave, Prophet Muhammad [s.a.w.s]. 

When the latter part of the verse is studied, i.e. "and hath allowed in it  no Crookedness".  ‘La hu’ can mean "he" or "it".  It is commonly translated to mean the Holy Qur’an; i.e. "it".  So if we take the meaning to mean it, the that part of the verse will mean that Allah has sent down the Qur’an and it contains no crookedness, defects, etc. 

‘Lahu’ in the above verse can also refer to Prophet Muhammad.  So if we read the and translate that "hu" to mean the Messenger, it will read like this: Praise be to Allah Who hath sent to His Servant the Book; and you will not find in "him" any crookedness.

How will you know what or who Allah is referring to?  Remember ‘the Qur’an explains itself’ so the other places in the Qur’an aid in your understanding.  This is why no one is authorised to explain the Qur’an.

With reference to the verse quoted above if you want to find support that Allah is speaking of the Qur’an when He attested that it contained no crookedness we can look at the following verse;

"It is the Quran in Arabic, without any crookedness therein; in order that they may guard against evil.' (39:28)

If you want take the word Lahu to mean the Prophet  we can find support for this in the following  verses; e.g.
 ‘And Verily, You (O Muhammad) are on an exalted standard of character’.  (68:4)
 ‘that Allah may forgive you your sins of the past and the future’.  (48:2)

Look at this one word when expounded upon has so many dimensions. 

It is important to understand the flawlessness of the Qur’an; and just as Allah produced a Book free from all kinds of defects; and the Messenger who brought the Book is also free from every form of defects,  we too need to make our book, that we are producing (i.e. our book of deeds) pure and as free from as much defects as possible. 

When a person requires a character certificate he needs to go to someone in authority such as a police officer.  And in order for the policeman to produce the certificate he will go through the records to see whether there were any ‘defects or crookedness’ in the person's life.  So too, on the Day of Judgment; in order to get into Paradise your book will be brought forward to see whether you have defects or good in it.

The Prophet  is our leader and exemplar and he was sinless which means that his book will contain no wrong or reprehensive deeds.  We must also aspire to purify our personalities so that on that Day our book will be one that we can feel proud of as a book free from records of crookedness  will grant us access to the Garden of bliss.

May Allah enable us to understand more and more of His Glorious Words and may He grant us the ability to cultivate our personalities in accordance with what is permissible, so that our book of deeds will be one that contains no crookedness nor defects.