Surah Al-Muzzammil 73:6

إِنَّ نَاشِئَةَ ٱلَّيْلِ هِىَ أَشَدُّ وَطْـًٔا وَأَقْوَمُ قِيلًا

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

Translation: Saheeh International

Tafsir

Assuredly rising in the night to wake up after having been in sleep is firmer in tread more conducive to establishing harmony between the hearing and the heart for the purpose of comprehending the Qur’ān and more upright in respect to speech clearer for utterance of devotions.

Excerpt from Tafsir al-Jalalayn, commentary on 73:6, via Quran.com. The reader has the full commentary and 9 more tafsirs.