Mishkat al-Masabih 1359
Abu Huraira said:
I went out to at-Tur and met Ka'b al-Ahbar with whom I sat, he telling me about the Torah and I telling him about God's Messenger. One of the things I told him was that God's Messenger had said, “The best day on which the sun has risen is Friday; on it Adam was created, on it he was cast down [from paradise], on it his repentance was accepted, on it he died, on it the last hour will come, on Friday every beast is on the outlook from dawn to sunrise from fear of the last hour, but not jinn and men, and it contains a time at which no Muslim will pray and ask anything from God without His giving him it." Ka'b said that was one day every year, but when I insisted that it was on every Friday Ka'b read the Torah and said that God's Messenger had spoken the truth. Abu Huraira said: I met ‘Abdallah b. Salam and told him of my meeting with Ka'b al-Ahbar and of what I had told him about Friday, telling him that Ka'b had said that was one day every year. ‘Abdallah b. Salam said that Ka'b had lied, but when I told him that Ka'b afterwards read the Torah and said that it was every Friday he said that Ka'b had spoken the truth. ‘Abdallah b. Salam then said that he knew what time it was, and when I asked him to tell me about it and not keep it to himself he replied that it was at the very end of Friday. I asked how that could be when God's Messenger had said, “No Muslim will pray in it . . . and he asked me if God’s Messenger had not said, “If anyone is seated waiting for the prayer he is engaged in the prayer until he observes it." When I replied that that was so he said that that was how it came about. 

Malik, Abu Dawud, Tirmidhi and Nasa’i transmitted it, and Ahmad transmitted it up to the statement that Ka'b had spoken the truth.
عَنْ أَبِي هُرَيْرَةَ قَالَ: خَرَجْتُ إِلَى الطُّورِ فَلَقِيتُ كَعْبَ الْأَحْبَارِ فَجَلَسْتُ مَعَهُ فَحَدَّثَنِي عَنِ التَّوْرَاةِ وَحَدَّثْتُهُ عَنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَكَانَ فِيمَا حَدَّثْتُهُ أَنْ قُلْتُ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: " خَيْرُ يَوْمٍ طَلَعَتْ عَلَيْهِ الشَّمْسُ يَوْمُ الْجُمُعَةِ فِيهِ خُلِقَ آدَمُ وَفِيهِ أُهْبِطَ وَفَيْهِ تِيبَ عَلَيْهِ وَفِيهِ مَاتَ وَفِيهِ تَقُومُ السَّاعَةُ وَمَا من دَابَّة إِلَّا وَهِي مسيخة يَوْمَ الْجُمُعَةِ مِنْ حِينِ تُصْبِحُ حَتَّى تَطْلُعَ الشَّمْسُ شَفَقًا مِنَ السَّاعَةِ إِلَّا الْجِنَّ وَالْإِنْسَ وفيهَا سَاعَةٌ لَا يُصَادِفُهَا عَبْدٌ مُسْلِمٌ وَهُوَ يُصَلِّي يسْأَل الله شَيْئا إِلَّا أعطَاهُ إِيَّاهَا. قَالَ كَعْبٌ: ذَلِكَ فِي كُلِّ سَنَةٍ يَوْمٌ. فَقلت: بل فِي كل جُمُعَة قَالَ فَقَرَأَ كَعْبٌ التَّوْرَاةَ. فَقَالَ: صَدَقَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ. قَالَ أَبُو هُرَيْرَةَ: لَقِيتُ عَبْدَ اللَّهِ بْنَ سَلَامٍ فَحَدَّثْتُهُ بِمَجْلِسِي مَعَ كَعْب وَمَا حَدَّثْتُهُ فِي يَوْمِ الْجُمُعَةِ فَقُلْتُ لَهُ: قَالَ كَعْب: ذَلِك كُلِّ سَنَةٍ يَوْمٌ؟ قَالَ عَبْدُ اللَّهِ بْنُ سَلَامٍ: كَذَبَ كَعْبٌ. فَقُلْتُ لَهُ ثُمَّ قَرَأَ كَعْبٌ التَّوْرَاةَ. فَقَالَ: بَلْ هِيَ فِي كُلِّ جُمُعَةٍ. فَقَالَ عَبْدُ اللَّهِ بْنُ سَلَامٍ: صَدَقَ كَعْبٌ ثُمَّ قَالَ عَبْدُ اللَّهِ بْنُ سَلَامٍ: قَدْ عَلِمْتُ أَيَّةَ سَاعَةٍ هِيَ. قَالَ أَبُو هُرَيْرَة فَقلت لَهُ: فَأَخْبرنِي بهَا. فَقَالَ عَبْدُ اللَّهِ بْنُ سَلَامٍ: هِيَ آخِرُ سَاعَةٍ فِي يَوْمِ الْجُمُعَةِ. قَالَ أَبُو هُرَيْرَةَ: فَقُلْتُ: وَكَيْفَ تَكُونُ آخِرَ سَاعَةٍ فِي يَوْمِ الْجُمُعَةِ وَقَدْ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَا يُصَادِفُهَا عَبْدٌ مُسْلِمٌ وَهُوَ يُصَلِّي وَتلك السَّاعَة لَا يُصَلِّي فِيهَا؟» فَقَالَ عَبْدُ اللَّهِ بْنُ سَلَامٍ: أَلَمْ يَقُلْ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ جَلَسَ مَجْلِسًا يَنْتَظِرُ الصَّلَاةَ فَهُوَ فِي صَلَاةٍ حَتَّى يُصَلِّيَ؟» قَالَ أَبُو هُرَيْرَةَ: فَقلت: بلَى. قَالَ: فَهُوَ ذَاك. رَوَاهُ مَالِكٌ وَأَبُو دَاوُدَ وَالتِّرْمِذِيُّ وَالنَّسَائِيُّ وَرَوَى أَحْمد إِلَى قَوْله: صدق كَعْب