All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The Quran is a book of guidance for mankind. Allaah revealed it for reflection. Allaah Says (what means): {[This is] a blessed Book which We have revealed to you, [O Muhammad], that they might reflect upon its verses and that those of understanding would be reminded.} [Quran 38:29]
The Companions used to ask the Messenger of Allaah about those verses of the Quran they found difficult to understand. Ibn Mas‘ood narrated that when the verse {They who believe and do not mix their belief with injustice} [Quran 6:82] was revealed, the Companions of the Messenger of Allaah were distressed and said: “Which of us is not unjust to himself?” The Messenger of Allaah said: “It is not as you think. Rather, it is as Luqmaan said to his son: {“O my son, do not associate [anything] with Allaah. Indeed, association [with Him] is great injustice.”} [Quran 31:13].” [Al-Bukhari and Muslim]
Likewise, the Companions, used to explain the Quran to the Taabi‘een [those who came after them]; Mujaahid said: “I went through the Mus-haf three times with Ibn ‘Abbaas, each time from its beginning to its end. I would stop after each verse and ask him about it.”
Therefore, many Muslim scholars dedicated themselves to Tafseer [interpretation of the Quran] and compiled books thereon and they continue to do so. In fact, we have never found anything from the books of knowledge that any of the scholars ever forbade people from learning the interpretation of the Quran. Rather, they warned people from presenting opinions about the Quran without knowledge.
Besides, the scholars laid down some principles for Tafseer upon which this science (of Tafseer) is based. They even compiled independent books on the subject, like the book Usool At-Tafseer by Ibn Taymiyyah ; or they included these principles in books of Tafseer, just as Ibn Katheer did in the introduction to his Tafseer. For more benefit, please refer to Fataawa 192685 and 90244.
As for the opinion of forbidding the Tafseer of the Quran, on the basis that it is sufficient to recite it (without understanding), then, as far as we know, no one of the trustworthy Muslim scholars has ever said such a thing. Instead, this is only a matter in the minds of some laymen and we do not know when exactly such ideas started to appear. What laymen say (about matters of religion) should not be given attention. Rather, they should be guided to the truth through wisdom and good admonition.
For more information, please refer to Fatwa 85360 and Fatwa 91554 regarding the virtue and etiquette of reflecting over the Quran and its recitation.
Allaah Knows best.