Ali Bin Muhammad, from Sahl Bin Ziyad, from Muhammad Bin Al Hassan, from Abdullah Bin Abdul Rahman, from Misma’a Bin Abdul Malik, ‘He -asws said: ‘When you have prayed Salāt Al-Al-Zohr, so the time for Al-Al-Asr has entered until there happens to be an Optional ( Salāt ) in front of it. So that is up to you. If you so desire to, you prolong, and if you so desire to, you shorten (the Optional Salāt )’.
[6] During the long days or when there is no urgent need to attend, one may offer two Salāts without combining those, i.e., Azan and Aqamah Al-Al-Zohr and optional Salāts and then at Al-Asr time, Azan and Aqamah Al-Al-Asr Salāt followed by optional Salāts. Why optional Salāt? A Believer would recite 51 Rak’ats in 24 hours!
مُحَمَّدُ بْنُ الْحَسَنِ عَنْ سَهْلٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ قَالَ قُلْتُ لِأَبِي الْحَسَنِ ( عليه السلام ) إِنَّ أَصْحَابَنَا يَخْتَلِفُونَ فِي صَلَاةِ التَّطَوُّعِ بَعْضُهُمْ يُصَلِّي أَرْبَعاً وَ أَرْبَعِينَ وَ بَعْضُهُمْ يُصَلِّي خَمْسِينَ فَأَخْبِرْنِي بِالَّذِي تَعْمَلُ بِهِ أَنْتَ كَيْفَ هُوَ حَتَّى أَعْمَلَ بِمِثْلِهِ فَقَالَ أُصَلِّي وَاحِدَةً وَ خَمْسِينَ Muhammad Bin Al Hassan, from Sahl, from Ahmad Bin Muhammad Bin Abu NAAsr who said, ‘I said to Abu Al-Hassan -asws , ‘Our companions are differing regarding the voluntary Salāts .
Some of them are praying forty-four ( Rak’at ), and some of them are praying fifty ( Rak’at ). So, inform me with which are you -asws acting upon, how it is so that I can act upon the like of it’. So he -asws said: ‘I -asws pray fifty-one (51) Rak’at ’.