From the information in the preceding chapter concerning the historical development of the tafsîr, its correct methodology, and examples of deviant tafsîrs, the following conditions could be deduced as necessary for the achievement of an authentic tafsîr of Qur’ân. Conversely, the omission of any one of the following conditions will more than likely result in a distorted interpretation of the Qur’ân.
1. Correct Belief
The mufassir  first and foremost must possess a true belief in Islâm for his or her tafsîr to be pure and free from heresy or gross errors. Sincerely believing in Islâm does not automatically mean that one who does so has true belief in Islâm. A true or correct belief exists only when one’s conception of Islâm coincides with that of the Prophet [sall-Allâhu ‘alayhi wa sallam] and his Companions. Ignorance of what constitutes correct belief in Islâm will almost certainly lend the mufassir into incorrect explanations. Such an individual will be unable to distinguish between a correct interpretation and an incorrect one. Consequently, he or she will have to rely on their personal judgment, which would be impaired due to their ignorance. Correct belief is also non-sectarian. Such a belief frees the mufassir from the damaging influence of philosophies, schools of thought (madhhabs), movements, and sects.  The mufassir does not approach the Qur’ân with preconceived ideas and notions for which he or she wishes to find support in the Qur’ân. Such an approach invariably leads to misinterpretations and sectarian explanations.
2. Correct Methodology
All honest attempts at tafsîr must begin with the tafsîr of the Qur’ân by Qur’ân itself. What remains unexplained must then be sought in the Sunnah. If the tafsîr still cannot be found, the explanations of the Sahâbah [Companions of the Prophet] and their students must then be turned to. That which is left after the preceding steps can be found in the language of the Qur’ân. Such an approach to tafsîr takes into account Allâh’s role as the revealer and explainer of His revelation, the Prophet’s role as the practical interpreter of Allâh’s revelation, the Sahâbah and their students’ roles as the conveyers of Allâh’ revelation and the Prophet’s interpretation and application of it, and the role of classical Arabic as the vehicle in which the revelation and its explanation were transmitted.
Any other approach negates one or more of these vital roles and implies either a claim of direct revelation from God or an understanding superior to that of the Prophet [sall-Allâhu ‘alayhi wa sallam] and his Companions. A brief glance at the tafsîr of those ignoring these steps will expose their claims to divine revelation cloaked in terms like “ilham” [inspiration] and “kashf” [illumination].
3. Correct knowledge
The mufassir must have working knowledge of classical Arabic, its grammatical constructions, and its figures of speech, because this is the language of the Qur’ân. Any tafsîr which is based solely on a translation of some of the meanings of the Qur’ân will be liable to distortion. As Mujâhid, the student of Ibn ‘Abbâs said:
“It is not allowable for anyone who believes in Allah and the Last Day to explain Allah’s Book if he is not knowledgeable in the Arabic language.” 
The mufassir should also know the other Islâmic sciences which are connected in one way or another to the Qur’ân, such as hadîth and fiqh [Islâmic law]. He should be familiar with the science of hadîth in order to make sure that explanations attributed the Prophet [sall-Allâhu ‘alayhi wa sallam] or his Companions that he uses in his tafsîr are authentic. He should also know the fundamental principles of fiqh [Usûl-ul-Fiqh] in order to accurately extract or deduce Islâmic law from its passages. Without a correct understanding of these two sciences, the mufassir could not possibly escape including in his tafsîr a wealth of misinformation, since the body of weak and fabricated narrations is quite vast and the schools of fiqh [Islâmic law] and their methods are many and varied.
By Dr. Abû Amînah Bilal Philips
Usûl at-Tafsîr: The Methodology of Qur’ânic Interpretation, Pgs. 51-53
1. One who makes tafsîr of the Qur’ân.
2. Mabahith fi ‘Ulûm al-Qur’ân, Pgs. 329-30
3. Quoted in Mabahith fi ‘Ulûm al-Qur’ân, Pgs. 331