It is He Who has sent down to you (Muhammad) the Book (this Quran). In it are Verses that are entirely clear, they are the foundations of the Book, and others not entirely clear. So as for those in whose hearts there is a deviation (from the truth) they follow that which is not entirely clear thereof, seeking al-Fitnah, and seeking for its hidden meanings, but none knows its hidden meanings save Allah. And those who are firmly grounded in knowledge say: "We believe in it; the whole of it (clear and unclear Verses) are from our Lord." And none receive admonition except men of understanding.
Umar bin al-Khattaab (may Allaah be pleased with him) said: There will come people who will dispute with you using the shubuhaat [unclear] Verses of the Qur’aan. So, answer them with the use of the Sunnah, for indeed the al-sahaab [Companions] of the Sunnah are the ones who have more knowledge of the Book of Allaah.
[Sunan al-Daarimi Narration No. 121]