Chapter on the Reward of Suhoor
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 2|Chapter 22
وَ قَالَ اَلنَّبِيُّ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: «تَعَاوَنُوا بِأَكْلِ اَلسَّحُورِ عَلَى صِيَامِ اَلنَّهَارِ وَ بِالنَّوْمِ عِنْدَ اَلْقَيْلُولَةِ عَلَى قِيَامِ اَللَّيْلِ».
The Prophet (peace be upon him and his family) said: "Strengthen yourselves for the fasting of the day by eating suhoor, and for the night prayer by taking a nap during the midday rest (qaylulah)."
- Ṣaḥīḥ al-Faqīh