١٦ـ عَلِيُّ بْنُ مُحَمَّدٍ وَمُحَمَّدُ بْنُ الْحَسَنِ عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ إِسْمَاعِيلَ بْنِ مِهْرَانَ قَالَ كَتَبْتُ إِلَى الرِّضَا (عَلَيْهِ الْسَّلام) ذَكَرَ أَصْحَابُنَا أَنَّهُ إِذَا زَالَتِ الشَّمْسُ فَقَدْ دَخَلَ وَقْتُ الظُّهْرِ وَالْعَصْرِ وَإِذَا غَرَبَتْ دَخَلَ وَقْتُ الْمَغْرِبِ وَالْعِشَاءِ الآخِرَةِ إِلاَّ أَنَّ هَذِهِ قَبْلَ هَذِهِ فِي السَّفَرِ وَالْحَضَرِ وَأَنَّ وَقْتَ الْمَغْرِبِ إِلَى رُبُعِ اللَّيْلِ فَكَتَبَ كَذَلِكَ الْوَقْتُ غَيْرَ أَنَّ وَقْتَ الْمَغْرِبِ ضَيِّقٌ وَآخِرُ وَقْتِهَا ذَهَابُ الْحُمْرَةِ وَمَصِيرُهَا إِلَى الْبَيَاضِ فِي أُفُقِ الْمَغْرِبِ. 
16. Ali ibn Muhammad and Muhammad ibn al-Hassan have narrated from Sahl ibn Ziyad from ’Isma‘il ibn Mehran who has said the following: “I once, wrote to al-Rida’ , to ask a question. ‘Our people have said that when the sun declines toward the west at noontime, it is the time of al-Dhuhr and al-‘Asr Salah (prayers). When it is sunset it is time of al-Maghrib and al-‘Isha’ al-Akhirah Salah (prayers) except that this is before this. It is the same for one at home or on a journey and the time of al-Maghrib remains until passing of one-fourth of night.’ He (the Imam) wrote to me, ‘That is how the timing is, except that the time of al- Maghrib is short and its end is when redness disappears, turning to whiteness in the western horizon.’” 