The Reward of the Night Prayer
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 65
وَقَالَ أَبُو اَلْحَسَنِ اَلْأَوَّلُ عَلَيْهِ اَلسَّلاَمُ: فِي قَوْلِ اَللَّهِ عَزَّ وَ جَلَّ «وَ رَهْبٰانِيَّةً اِبْتَدَعُوهٰا مٰا كَتَبْنٰاهٰا عَلَيْهِمْ إِلاَّ اِبْتِغٰاءَ رِضْوٰانِ اَللّٰهِ» قَالَ «صَلاَةُ اَللَّيْلِ.
Abu al-Hasan al-Awwal عليه السلام said regarding the words of Allah سبحانه وتعالى, the Mighty and Majestic: "But as for monasticism, they innovated it; We did not prescribe it for them except [that they did so] seeking the pleasure of Allah سبحانه وتعالى" (Surah Al-Hadid 57:27). Imam عليه السلام said: "It refers to the night prayer (salat al-layl)."
- Ṣaḥīḥ al-Faqīh