Al-Kāfi - Volume 3 > The Time for Friday and ‘Asr Salah (prayer)
Hadith #4

4ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ مُحَمَّدِ بْنِ خَالِدٍ عَنِ الْقَاسِمِ بْنِ عُرْوَةَ عَنْ مُحَمَّدِ بْنِ أَبِي عُمَيْرٍ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ الْسَّلام) عَنِ الصَّلاَةِ يَوْمَ الْجُمُعَةِ فَقَالَ نَزَلَ بِهَا جَبْرَئِيلُ (عَلَيْهِم الْسَّلام) مُضَيَّقَةً إِذَا زَالَتِ الشَّمْسُ فَصَلِّهَا قَالَ قُلْتُ إِذَا زَالَتِ الشَّمْسُ صَلَّيْتُ رَكْعَتَيْنِ ثُمَّ صَلَّيْتُهَا فَقَالَ قَالَ أَبُو عَبْدِ الله (عَلَيْهِ الْسَّلام) أَمَّا أَنَا إِذَا زَالَتِ الشَّمْسُ لَمْ أَبْدَأْ بِشَيْ‏ءٍ قَبْلَ الْمَكْتُوبَةِ قَالَ الْقَاسِمُ وَكَانَ ابْنُ بُكَيْرٍ يُصَلِّي الرَّكْعَتَيْنِ وَهُوَ شَاكٌّ فِي الزَّوَالِ فَإِذَا اسْتَيْقَنَ الزَّوَالَ بَدَأَ بِالْمَكْتُوبَةِ فِي يَوْمِ الْجُمُعَةِ.

4. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn Khalid from al-al-Qasim ibn ‘Urwah from Muhammad ibn abu ‘Umayr who has said the following: “I once asked abu ‘Abd Allah, ‘Alayhi al-Salam, about Salah (prayer) of Friday. He (the Imam) said, ‘ Jibril brought it with a short period of time. When it is Zawal (declining of the sun toward the west at noontime) then perform it.’ I (the narrator) then asked, ‘When it is Zawal, must I perform two Rak‘at, then Friday Salah (prayer)?’ Abu ‘Abd Allah, ‘Alayhi al-Salam, said, ‘I, however, when it is Zawal, do not begin anything before obligatory Salah (prayer).’ Al-Qasim has said that ibn Bukayr would perform two Rak‘at when he had doubts about the commencement of Zawal. When he became certain of the commencement of Zawal he commenced the obligatory Salah (prayer) on Friday.’” (The following chapter is best explained in the form of fatwa.)