Prayer Times

Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 33
وَ سَأَلَ زُرَارَةُ أَبَا جَعْفَرٍ اَلْبَاقِرَ عَلَيْهِ اَلسَّلاَمُ: عَنْ وَقْتِ اَلظُّهْرِ فَقَالَ «ذِرَاعٌ مِنْ زَوَالِ اَلشَّمْسِ وَ وَقْتُ اَلْعَصْرِ ذِرَاعَانِ مِنْ وَقْتِ اَلظُّهْرِ فَذَاكَ أَرْبَعَةُ أَقْدَامٍ مِنْ زَوَالِ اَلشَّمْسِ» ثُمَّ قَالَ «إِنَّ حَائِطَ مَسْجِدِ رَسُولِ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ كَانَ قَامَةً وَ كَانَ إِذَا مَضَى مِنْهُ ذِرَاعٌ صَلَّى اَلظُّهْرَ وَ إِذَا مَضَى مِنْهُ ذِرَاعَانِ صَلَّى اَلْعَصْرَ » ثُمَّ قَالَ «أَ تَدْرِي لِمَ جُعِلَ اَلذِّرَاعُ وَ اَلذِّرَاعَانِ» قُلْتُ لِمَ جُعِلَ ذَلِكَ قَالَ «لِمَكَانِ اَلنَّافِلَةِ لَكَ أَنْ تَتَنَفَّلَ مِنْ زَوَالِ اَلشَّمْسِ إِلَى أَنْ يَمْضِيَ ذِرَاعٌ فَإِذَا بَلَغَ فَيْئُكَ ذِرَاعاً بَدَأْتَ بِالْفَرِيضَةِ وَ تَرَكْتَ اَلنَّافِلَةَ وَ إِذَا بَلَغَ فَيْئُكَ ذِرَاعَيْنِ بَدَأْتَ بِالْفَرِيضَةِ وَ تَرَكْتَ اَلنَّافِلَةَ.
Zurarah asked Imam Muhammad ibn Ali Al-Baqir عليه السلام about the timing of the Dhuhr (noon) prayer. Imam عليه السلام replied: "It is one arm's length (shadow) from the sun's decline, and the time for Asr (afternoon) is two arm's lengths from the time of Dhuhr, which is four feet from the sun's decline." He then added, "The wall of the Prophet’s Mosque صلى الله عليه وعلى آله وسلم was as high as a person's stature, and when a shadow reached one arm's length, the Dhuhr prayer would be performed, and when it reached two arm's lengths, the Asr prayer would be performed." He then asked: "Do you know why the measure of one and two arm's lengths was set?" I said: "Why was that made so?" Imam عليه السلام said: "It is for the sake of the supererogatory (nafilah) prayers. You may perform the supererogatory prayers from the sun's decline until the shadow reaches one arm's length; when it reaches one arm's length, you begin the obligatory prayer and leave the supererogatory prayer. When it reaches two arm's lengths, you begin the obligatory prayer and leave the supererogatory prayer."
  • Shaykh Baqir al-Behbudi
    Ṣaḥīḥ al-Faqīh, p. 34