The Time for Night Prayer
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 66
وَقَالَ عُمَرُ بْنُ حَنْظَلَةَ لِأَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: إِنِّي مَكَثْتُ ثَمَانِيَ عَشْرَةَ لَيْلَةً أَنْوِي اَلْقِيَامَ فَلاَ أَقُومُ أَ فَأُصَلِّي أَوَّلَ اَللَّيْلِ قَالَ «لاَ اِقْضِ بِالنَّهَارِ فَإِنِّي أَكْرَهُ أَنْ يُتَّخَذَ ذَلِكَ خُلُقاً.
Umar ibn Hanzalah said to Imam Jafar ibn Muhammad Al-Sadiq عليه السلام: "I have spent eighteen nights intending to rise (for the night prayer) but did not get up. Should I then pray at the beginning of the night?" He عليه السلام replied: "No, make it up during the day, for I dislike it becoming a habitual practice."
- Ṣaḥīḥ al-Faqīh