Al-Kāfi - Volume 3 > The Time for Friday and ‘Asr Salah (prayer)
Hadith #2

2ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ مُحَمَّدِ بْنِ عِيسَى عَنْ يُونُسَ بْنِ عَبْدِ الرَّحْمَنِ عَنْ عَبْدِ الله بْنِ سِنَانٍ قَالَ قَالَ أَبُو عَبْدِ الله (عَلَيْهِ الْسَّلام) إِذَا زَالَتِ الشَّمْسُ يَوْمَ الْجُمُعَةِ فَابْدَأْ بِالْمَكْتُوبَةِ.

2. Ali ibn Ibrahim has narrated from Muhammad ibn ‘Isa from Yunus ibn ‘Abd al-Rahman from ‘Abd Allah ibn Sinan who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘On Friday when it is Zawal (declining of the sun to ward the west at noontime), then you can begin the obligatory Salah (prayer).”’