1319 - وَ سَأَلَ سَعِيدُ بْنُ اَلْمُسَيَّبِ عَلِيَّ بْنَ اَلْحُسَيْنِ عَلَيْهِمَا اَلسَّلاَمُ فَقَالَ لَهُ: مَتَى فُرِضَتِ اَلصَّلاَةُ عَلَى اَلْمُسْلِمِينَ عَلَى مَا هِيَ اَلْيَوْمَ عَلَيْهِ فَقَالَ « بِالْمَدِينَةِ حِينَ ظَهَرَتِ اَلدَّعْوَةُ وَ قَوِيَ اَلْإِسْلاَمُ وَ كَتَبَ اَللَّهُ عَزَّ وَ جَلَّ عَلَى اَلْمُسْلِمِينَ اَلْجِهَادَ زَادَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ فِي اَلصَّلاَةِ سَبْعَ رَكَعَاتٍ فِي اَلظُّهْرِ رَكْعَتَيْنِ وَ فِي اَلْعَصْرِ رَكْعَتَيْنِ وَ فِي اَلْمَغْرِبِ رَكْعَةً وَ فِي اَلْعِشَاءِ اَلْآخِرَةِ رَكْعَتَيْنِ وَ أَقَرَّ اَلْفَجْرَ عَلَى مَا فُرِضَتْ بِمَكَّةَ لِتَعْجِيلِ عُرُوجِ مَلاَئِكَةِ اَللَّيْلِ إِلَى اَلسَّمَاءِ وَ لِتَعْجِيلِ نُزُولِ مَلاَئِكَةِ اَلنَّهَارِ إِلَى اَلْأَرْضِ فَكَانَتْ مَلاَئِكَةُ اَلنَّهَارِ وَ مَلاَئِكَةُ اَللَّيْلِ يَشْهَدُونَ مَعَ رَسُولِ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ صَلاَةَ اَلْفَجْرِ فَلِذَلِكَ قَالَ اَللَّهُ تَبَارَكَ وتَعَالَى «وَ قُرْآنَ اَلْفَجْرِ إِنَّ قُرْآنَ اَلْفَجْرِ كٰانَ مَشْهُوداً » يَشْهَدُهُ اَلْمُسْلِمُونَ وَ تَشْهَدُهُ مَلاَئِكَةُ اَلنَّهَارِ وَ مَلاَئِكَةُ اَللَّيْلِ.
Hadith.1319 - Sa'id ibn al-Musayyib asked Ali ibn al-Hussain 
,
"When was the prayer made obligatory upon the Muslims in the form it is today?"
He replied: "In Medina, when the call (to Islam) became manifest, Islam was strengthened, and Allah (swt), the Mighty and Majestic, prescribed jihad upon the Muslims.
The Messenger of Allah ﷺ added seven rak'ahs to the prayers: two to Dhuhr, two to Asr, one to Maghrib, and two to the Isha prayer, while leaving the Fajr prayer as it had been prescribed in Mecca.
This was to hasten the ascent of the night’s angels to the heavens and the descent of the day’s angels to the earth. Thus, the angels of the night and the angels of the day would witness the Fajr prayer with the Messenger of Allah ﷺ.
This is why Allah (swt), Blessed and Exalted, said: 'Recite the Qur'an at dawn. Indeed, the recitation of the Qur'an at dawn is ever witnessed' (Qur'an 17:78) — witnessed by the Muslims and by the angels of the night and the angels of the day."
