أو زد عليه ورتل القرآن ترتيلا (73:4) بالانجليزي

(73:4) or add to it a little; *3 and recite the Qur'an slowly and distinctly. *4

Tafseer Abu-al-A'la Maududi

Page 574 English Traditional

*3) This is an explanation of the duration of time commanded to be spent in worship. In it the Holy Prophet (upon whom be peace) was given the option to spend half of the night in the Prayer, or a little less than that, or a little more than that. But the style shows that half the night has been regarded as preferable, for the measure is the same, which may be decreased or increased, as the people may like and choose.
*4) "Recite the Qur'an ......": Do not recite it quickly and in haste, but slowly and distinctly: pause at every verse so that the mind understands the meaning and purport of Divine Revelation well and takes effect from it. if it contains the mention of Allah's Being and Attributes, it may awe-inspire the heart with His glory and majesty; if it expresses His mercy, the heart may be filled with feelings of gratitude to Him; if it mentions His wrath and His punishment, the heart may be overwhelmed by fear of Him; if it enjoins something or forbids something, one may understand what has been enjoined and what has been forbidden. In short, the recital dces not only consist in uttering the words with the tongue, but it should involve thoughtful consideration of the meaning. When Hadrat Anas was asked about the Holy Prophet's method of reciting the Qur'an, he replied: The Holy Messenger stretched the words when reciting them. For example, when he recited Bismillah ir-Rahman it-Rahim he would stretch and prolong the sound of AIIah, Rahman and Rahim (Bukhari). When Hadrat Umm Salamah was asked the same question, she replied that the Holy Prophet (upon whom be peace) recited every verse separately and distinctly and observed a pause at the end of every verse. For instance, he recited AI-hamdu-lillah-i Rabb-il'alamin, and paused, then recited ar-Rahman ir-Rahim, and paused, and then recited Malik-i yaum id-di'n. "(Musnad Ahmad, Abu Da'ud, Tirmidhi). In another tradition, Hadrat Umm Salamah has stated that the Holy Prophet recited each word distinctly and clearly. (Tirmidhi, Nasa'i). Hadrat Hudhaifah bin Yaman says: "Once I stood beside the Holy Prophet in the Night Prayer to see how he recited the Qur'an. I noticed that he glorified Allah where He should be glorified, invoked and supplicated Allah where He should be invoked and supplicated, and sought refuge of Allah where His refuge should be sought." (Muslim, Nasa'i). Hadrat Abu Dharr has stated that once during the Night Prayer when the Holy Prophet (upon whom be peace) came to the sentence: In to adhdhib-hmn ... (If You punish them, then they are Your servants; and if You forgive them, then You are Almighty, All-Wise), he went on repeating it over and over again until it became dawn." (Musnad Ahmad, Bukhari).