Surah Al-Muzzammil — Ayah 6 (73:6)

English translation (Saheeh International)

Indeed, the hours of the night are more effective for concurrence [of heart and tongue]¹ and more suitable for words.²

1. Another accepted interpretation of the same words is "Indeed, arising at night is more difficult...," meaning that it will only be done by sincere believers and not others.
2. i.e., for recitation of the Qur’ān and for hearing and understanding it.

Brief commentary

The hours of the night are more suited to the heart for recitation and more correct in speech.