how does the qur'an lend itself to interpretation?

The answer to this question is contained in the previous section where we discussed the eternal validity of the Qur'an: it speaks to, instructs and guides man now as it did in the past.
As we have seen, the whole text of the Qur'an is a challenge to mankind and particularly to the enemies of Islam in that the Qur'an itself is proof of its own argument; it announces itself as a light, an illumination and an explanation of all things.
Thus a document which states and demonstrates that it is self-illuminating, hardly needs others to illuminate it. As proof that it is not the speech of man, the Qur'an says that it is a harmonious speech, without the slightest inconsistency and any seeming inconsistency may be removed through reflection on the Qur'an itself. If it were not the word of God, the Qur'an would not be as clear as it is.
Moreover, if such speed needed something or someone else to explain its meaning and purpose, it would neither be the proof nor the absolute authority that it is so obviously is. This clarity is absolute, even if a seemingly contradictory passage becomes the object of dispute; it could be understood by cross-reference to the text of the qur'an.
For instance, at the time of the Prophet, such matters could be referred to him since his knowledge of the Qur'an was perfect and he did not need to refer to other verses for clarification. Those who insisted on disagreeing, or disbelieving in the prophet's fallibility, were not satisfied.
Therefore, commentaries which solve problems of interpretation by quoting the commentaries of the Prophet, without giving proofs from other Qur'anic verses, are useful only for those who believe in Prophethood and the Prophet's infallibility. These people do not go unmentioned in the Qur'an; we are familiar with the following verse, if it had been from other than god then they would have found many inconsistencies in it.
This is a clear argument against those who would seek for inconsistencies in the qur'an and find fault with the prophet.
The Qur'an itself declares that the commentary and explanation of the Prophet is valid while the Prophet himself has confirmed the validity of the Qur'anic commentary of the Imams. We may summarize this by saying that in the Qur'an some verses may be explained by comparison with other verses and some by using the instructions and teachings of the Prophet and the Imams. The latter commentaries are not, of course, different from the explanation which is produced by comparing and analysing different verses.