Ali Bin Muhammad, from Muhammad Bin Musa, from Muhammad Bin Isa, from Ibn Fazzal, from Hammad Bin Usman who said, ‘Muhammad Bin Hakeym narrated to me saying, ‘I heard Abu Al-Hassan -asws saying: ‘The gathering between the two Salāt is when there does not happen to be Optional Salāts between the two. So, when there were Optional Salāts between the two, so do not gather’.
[2] وَ بِسَنَدٍ فِيهِ ضَعْفٌ عَنْ مُحَمَّدِ بْنِ حَكِيمٍ عَنْ أَبِي الْحَسَنِ ع قَالَ سَمِعْتُهُ يَقُولُ إِذَا جَمَعْتَ بَيْنَ الصَّلَاتَيْنِ فَلَا تَطَوَّعْ بَيْنَهُمَا And with a weak sanad (chain of narrators) on the authority of Muhammad bin Hakim on the authority of Abu Al-Hasan -asws , he said I heard him say that if you combine the two prayers, do not (offer) optional Salāt between them.
[3] However, when we are pressed against time or have a valid reason, we can combine the two Salāts with one Azan and two Aqamah, for example: عَلِيُّ بْنُ مُحَمَّدٍ عَنِ الْفَضْلِ بْنِ مُحَمَّدٍ عَنْ يَحْيَى بْنِ أَبِي زَكَرِيَّا عَنْ أَبَانٍ عَنْ صَفْوَانَ الْجَمَّالِ قَالَ صَلَّى بِنَا أَبُو عَبْدِ اللَّهِ ( عليه السلام ) الظُّهْرَ وَ الْعَصْرَ عِنْدَ مَا زَالَتِ الشَّمْسُ بِأَذَانٍ وَ إِقَامَتَيْنِ وَ قَالَ إِنِّي عَلَى حَاجَةٍ فَتَنَفَّلُوا .
Ali Bin Muhammad, from Al Fazl Bin Muhammad, from Yahya Bin Abu Zakariyya, from Aban, from Safwan Al Jammal who said, ‘Abu Abdullah -asws prayed with us Al-Al-Zohr and Al-Al-Asr Salāt during the (start of the) decline of the sun, with one Azan and two Aqamahs, and said: ‘I -asws am upon a need, so pray Optional Salāts ’.
Ali Bin Ibrahim, from his father, from Ibn Abu Umeyr, from Dareeh Al Muharby who said, ‘I said to Abu Abdullah -asws , ‘When shall I pray Al-Zohr?’ So he -asws said: ‘Pray eight ( Rak’at ) of Salāt then pray Al-Al-Zohr.