Hadith

Rasulullah (sallallahu alayhi wa sallam) said, "Whoever says something in interpreting the Qur'an based on his own opinion should find his place in the Fire." (Tirmizi)

Interpreting the Qur'an requires expertise in several areas. Scholars have prescribed seven sciences as a prerequisite for interpretation. Unfortunately, today a lot of well meaning people are attempting to interpret without any qualification. They start, say, a Qur'anic study group, and start giving lectures on Qur'an. If the person is a good speaker, he might also get warm reception from an audience that confuses eloquence with scholarship. Soon, they start giving expert opinions about Shariah and Qur’an without having even the minimum qualification for it. Many a time, the audience participates equally excitedly, discussing the Words of Allah Ta’ala and delicate issues of Shariah with the same assumed expertise that is normally reserved for discussion of latest current affairs.
This casual attitude must be contrasted with that of the Companions. They not only new the language of the Qur'an better then anyone else, they were witnesses to its very revelation. Yet, they did not dare interpret it without first learning it, verse by verse, from Prophet Muhammad (sallallahu alaihi wasallam) himself. And even then they exercised extreme caution.