Surah Al-Muzzammil Verse 6

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