Hamza, in his book دراسات الأحكام والنسخ في القرآن الكريم, pages 17-36, lists the different opinions of scholars about what is Muhkam and what is Mutashaabih. The inevitable conclusion from what the scholars said is that they did not agree on what the two words, specially Mutashaabih, mean, nor whether a Mutashaabih can be interpreted, nor who may interpret it, nor what the wisdom is behind it!
Doesn't that prove that the matter is indeterminate, and therefore should not be attempted? And isn't that exactly what 3:7 says?
Mutashaabih is there to test the faith of Muslims. Those who tell themselves they can interpret it and/or attempt to do so are either (a) have deviation (
زيغ) in their hearts, or (b) attempting the impossible!
Hamza stated that the consensus of the Sahaaba and the generation that followed them was that Mutashaabih cannot be interpreted and shouldn't be, but only accepted as part of the faith. He quotes Umm Salama, may God have been pleased with her, commenting on
saying "The how is unknown. The sitting up is not unknown. Admitting it is part of faith and denying it is blasphemy."
He, however, leans toward the opinion that a Mutashaabih can be interpreted a bit! He argues "what is the point, then, of contrasting those in whose hears is a deviation with those who are steep in knowledge?" He adds "Those steeped in knowledge are guided by God to interpretation."
Well, the point is obvious. The former attempt to interpret, fully aware that only God can do so, and the latter don't even try.