Surah Al-Muzzammil, Verse 6

إِنَّ نَاشِئَةَ ٱلَّيۡلِ هِيَ أَشَدُّ وَطۡـٔٗا وَأَقۡوَمُ قِيلًا٦

inna nāshi-ata al-layli hiya ashaddu waṭan wa-aqwamu qīlan

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