Allaah Says: "We have revealed unto thee the Remembrance that thou may make explain to mankind that which hath been revealed for them, and that haply they may reflect." [16:44]
We couldn't find explanation given by the Prophet, sallallaahu alayhi wa sallam, for every verse of the Quran. Most of the explanation of the Quranic verses in the Tafseer works reaches only back to the companions and successors of the Prophet, sallallaahu alayhi wa sallam. What is the correct interpretation of the verse and did the Prophet, sallallaahu alayhi wa sallam, explain every verse of the Quran? One of the scholars I asked said that the word "Tubayyina" in the verse only means to "read out" [in contrast to hide] and does not mean to explain, and he said that this is the interpretation given by Abu Layth Samarqandi in his Tafseer. Is it correct?

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. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Allaah described His Book as being a clear and plain Book in many verses. Allaah Says (what means): {Alif, Laam, Ra [these are on of the miracles of the Quran and none but Allaah knows their meanings]. These are the verses of the Book and a clear Quran [i.e. recitation].}[Quran 15:1]. Allaah Says (what means): {…and We have sent down to you a clear light.}[Quran 4:174]. Al-Qurtubi said: 'This means clarifying and illustrating, and it is clear (in itself).' Indeed there are many verses which describe the Quran as a clear and plain Book.

Furthermore, the companions were pure Arabs and the Quran was revealed in their language. They witnessed the revelation of the Quran and the reason why the verses were being revealed. It is for this reason that was not used to explain to them every verse but he used only the verses they found difficult to understand.

Saying that the meaning of the verse in which Allaah Says (what means): {…that you may make clear to the people what was sent down to them…}[Quran 16:44], is to recite to the people in a loud voice, is wrong. It was not permissible to act upon many religious rulings that were mentioned in the Quran just by listening to them from the Prophet but until he clarified and explained them in his Sunnah, like the prayer, the Zakat, Hajj and so forth. So saying what the verse means is just for the Prophet to recite to the people what was revealed to him without clarifying and explaining to them, is a wrong statement.

The Prophet explained many verses to the companions which they could not understand. 

Allaah Knows best.