Here, Allah (swt) ends the speech about the Day of Resurrection and its hardships to speak about the Guidance; the Holy Quran. Allah (swt) assures the Prophet (saws) that the Holy Quran is preserved because when the Revelation was sent down to him (saws), he used to repeat it word by word. For example, when the saying of Allah (swt): (Say, “It has been revealed to me”) (al-Jinn:1) was revealed to him, he used to repeat it inwardly after Jibril lest he forgets it. So, Allah (swt) prohibits him from rushing, saying:

وَلَا تَعْجَلْ بِالْقُرْآنِ مِن قَبْلِ أَن يُقْضَىٰ إِلَيْكَ وَحْيُهُ ۖ

(do not hasten with [recitation of] the Qur’an before its revelation is completed to you) (Ta-Ha: 114)

Meaning, ‘do not rush or pre-occupy yourself with repeating and rehearsing, for nothing will escape from your memory’. In another verse, Allah (swt) says:

 سَنُقْرِئُكَ فَلَا تَنسَىٰ

(We will make you recite, [O Muhammad], and you will not forget,) (Al-A’la: 6)

That is, when Jibril completes the recitation of the verses, he (saws) can recite them as he wishes. For, some quarters of the Holy Quran or even a complete Surah used to be sent down all at once to the Prophet (saws). When the Revelation departs him, the Prophet (saws) used to repat them exactly as they have been revealed. One of the wonders of the Holy Quran is that the Prophet (saws) was able to repeat the whole Surah as dictated to him. Whereas, no one can repeat his speech literally after talking for five minutes. In this verse of discussion, Allah (swt) orders the Prophet (saws) to relieve himself for he will not forget anything of the revelation, he should wait until the revelation of the verses ends and then he can repeat then without missing any letter thereof.