Hadith NO 4:

Narrated Said bin Jubair:

Ibn 'Abbas in the explanation of the Statement of Allah. 'Move not your tongue concerning (the Quran) to make haste therewith." (75.16) Said "Allah's Apostle used to bear the revelation with great trouble and used to move his lips (quickly) with the Inspiration." Ibn 'Abbas moved his lips saying, "I am moving my lips in front of you as Allah's Apostle used to move his." Said moved his lips saying: "I am moving my lips, as I saw Ibn 'Abbas moving his." Ibn 'Abbas added, "So Allah revealed 'Move not your tongue concerning (the Qur'an) to make haste therewith. It is for us to collect it and to give you (O Muhammad) the ability to recite it (the Qur'an) (75.16-17) which means that Allah will make him (the Prophet ) remember the portion of the Qur'an which was revealed at that time by heart and recite it. The Statement of Allah: And 'When we have recited it to you (O Muhammad through Gabriel) then you follow its (Qur'an) recital' (75.18) means 'listen to it and be silent.' Then it is for Us (Allah) to make It clear to you' (75.19) means 'Then it is (for Allah) to make you recite it (and its meaning will be clear by itself through your tongue). Afterwards, Allah's Apostle used to listen to Gabriel whenever he came and after his departure he used to recite it as Gabriel had recited it.

Commentary by Ibtisam Elahi Zaheer:

This hadith indicates two important things :

1  The sense of responsibility which prophet exhibited in his effort to memorise  holy inspiration coming to him .

2  The blessing of Allah on his prophet that how He made it easy for him to memorise holy inspiration.

It was actually the duty of Rasool salal laho aliehi wasalam to convey the message of Allah swt without any tampering as mentioned by Allah swt in Holy Quran:

O Messenger (Muhammad SAW)! Proclaim (the Message) which has been sent down to you from your Lord. And if you do not, then you have not conveyed His Message. Allâh will protect you from mankind. Verily, Allâh guides not the people who disbelieve. (Al-Ma'idah 5:67)

Therefore when angel Gabriel came to him with revelation he used to move his lips quickly to grasp the revelation coming to him.Allah swt was well aware of feeling of his prophet so he made it clear to him that he should not take burden of this thing .

Allah swt says:

And when We have recited it to you [O Muhammad SAW through Jibrael (Gabriel)], then follow you its (the Qur'ân's) recital. Then it is for Us (Allâh) to make it clear to you, (Al-Qiyamah 75:18-19)

These verses make it clear that Holy prophet salal laho aliehi wasalam did not only grasp the words of revelation but he the meanings of inspiration and its explanation was inspired by Allah swt.Therefore it can be easily concluded that Quran along with its meaning was inspired on Holy prophet salal laho aliehi wasalam .So we cannot by pass prophet salal laho aliehi wasalam while trying to understand Quran.

This fact has been mentione in the following way:

And We have not sent down the Book (the Qur'an) to you (O Muhammad SAW), except that you may explain clearly unto them those things in which they differ, and (as) a guidance and a mercy for a folk who believe. (An-Nahl 16:64)

On another instance Allah swt says:

And We have also sent down unto you (O Muhammad SAW) the reminder and the advice (the Qur'ân), that you may explain clearly to men what is sent down to them, and that they may give thought. (An-Nahl 16:44)

These verses of Quran indicate that prophet salal laho aliehi wasalam had full commands on the real meanings of Holy Quran and these meanings were also inspired on him besides the real text.So there are two sets of commands for Muslims One is book of Allah and other is its explanation also termed as hadith .These two sources of clear guidance were also mentioned by Rasool salal laho aliehi waslaam in his khutbah of Hajj that he left behind two sets of commands .One is book of Allah swt and other is sunnah of His Rasool salal laho aliehi waslam.

So coming back to the point initially prophet salal laho aliehi wasalam was conscious about memorisation of holy inspiration but Allah swt made it easy for His prophet . With the blessings of Allah swt he was capable of  memorising the revelation without any burden and hard work.