From Sh Fawzaan’s explanation of Sharh-us-Sunnah:

And harmonising the texts is what is obligatory.  If there are differences between texts, then as far as it is possible to harmonise between them, this must be done.  And this is clear; and all Praise is for Allaah.  And the Speech of Allaah can never contradict itself. Rather some parts of it explain other parts.  As for the person who takes one aayah and abandons a different ayaah, then this is from the people of deviation.  He the Most High said:

فَأَمَّا الَّذِينَ في قُلُوبِهِمْ زَيْغٌ فَيَتَّبِعُونَ مَا تَشَابَهَ مِنْهُ ابْتِغَاء الْفِتْنَةِ وَابْتِغَاء تَأْوِيلِهِ

(Explanation)

So as for those people in whose hearts is deviation, then they follow that which is unclear, seeking discord and seeking to falsely interpret it

(Soorah Aali `Imraan (3), aayah 7)

So evidence is taken from the Qur·aan in totality. 

كُلٌّ مِّنْ عِندِ رَبِّنَا 

 (Explanation)

All of it is from our Lord

(Soorah Aali `Imraan (3), aayah 7)

Just as the raasikhoon (those firmly grounded in knowledge) say.  So the Qur·aan, some parts of it explain the rest.  And there can never be any contradiction in it because Allaah has negated from it any contradiction.  He, the Most High, said:

أَفَلاَ يَتَدَبَّرُونَ الْقُرْآنَ وَلَوْ كَانَ مِنْ عِندِ غَيْرِ اللّهِ لَوَجَدُواْ فِيهِ اخْتِلاَفًا كَثِيرًا 

(Explanation)

Will they not ponder/reflect upon the Qur·aan.  If it had been from other than Allaah, they would certainly would have found in it many contradictions

(Sooratun-Nisaa· (4), aayah 82)

So if you have a problem in understanding an aayah, then you look into the Qur·aan for that which will explain it.  And if you do not find that, then you go to the Sunnah to find that which will explain it in the Sunnah.  And if you do not find its explanation in the Sunnah, then you go to the sayings of the Companions, those who narrated from the Messenger sallAllaahu ` alayhi wa sallam, to find in their sayings that which will explain the aayah which you have a problem in understanding.  The Qur·aan, and all Praise is for Allaah, is preserved in its wording and in its meaning.  It neither opposes nor contradicts itself, rather contradictions only occur in the understandings of mankind. 

And likewise those false claimants to knowledge, those who did not truly study knowledge and did not take the principles of deriving evidence and of how to reach conclusions, they derive proof without understanding (fiqh).  And they affirm things which no-one before them affirmed from the people of knowledge because of jahl, ignorance, and because of ta`aalum, pseudo-knowledge/false knowledge.  So these are tremendous matters which require learning and require precision and require careful consideration and require verification, because the `aqeedah (creed and belief) is the foundation.  And if there are deficiencies in it, this will be a deficiency in the foundation (of your religion).  

(Translated by Abu Talhah rahimahullaah)