The Reward of the Night Prayer
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 65
وَقَالَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «عَلَيْكُمْ بِصَلاَةِ اَللَّيْلِ فَإِنَّهَا سُنَّةُ نَبِيِّكُمْ وَ أَدَبُ اَلصَّالِحِينَ قَبْلَكُمْ وَ مَطْرَدَةُ اَلدَّاءِ عَنْ أَجْسَادِكُمْ.
Imam Jafar ibn Muhammad Al-Sadiq عليه السلام said: "You must engage in the night prayer (salat al-layl), for it is the tradition (sunnah) of your Prophet and the practice of the righteous before you, and it drives away illness from your bodies."
- Ṣaḥīḥ al-Faqīh