Al-Muzzammil 73:3

بِسْمِ اللَّهِ الرَّحْمَـٰنِ الرَّحِيمِ يَا أَيُّهَا الْمُزَّمِّلُ

O you who wraps himself [in clothing],

قُمِ اللَّيْلَ إِلَّا قَلِيلًا

Arise [to pray] the night, except for a little -

أَوْ زِدْ عَلَيْهِ وَرَتِّلِ الْقُرْآنَ تَرْتِيلًا

Or add to it, and recite the Qur'an with measured recitation.

إِنَّا سَنُلْقِي عَلَيْكَ قَوْلًا ثَقِيلًا

Indeed, We will cast upon you a heavy word.

إِنَّ نَاشِئَةَ اللَّيْلِ هِيَ أَشَدُّ وَطْئًا وَأَقْوَمُ قِيلًا

Indeed, the hours of the night are more effective for concurrence [of heart and tongue] and more suitable for words.