[Machine] While the Prophet of Allah (PBUH) was giving a sermon on Friday, Abu Dharr said to Abu bin Ka'b, "When was this Surah revealed?" He did not respond, so when he finished his prayer, he said to him, "You have not received any reward for your prayer except what you have wasted." Abu Dharr then went to the Prophet (PBUH) and told him about it, and he said, "Abu Dharr has spoken the truth."  

بَيْنَمَا رَسُولُ اللهِ ﷺ يَخْطُبُ يَوْمَ الْجُمُعَةِ إِذْ قَالَ أَبُو ذَرٍّ لِأُبِيِّ بْنِ كَعْبٍ مَتَى أُنْزِلَتْ هَذِهِ السُّورَةُ؟ فَلَمْ يُجِبْهُ فَلَمَّا قَضَى صَلَاتَهُ قَالَ لَهُ مَا لَكَ مِنْ صَلَاتِكَ إِلَّا مَا لَغَوْتَ فَأَتَى أَبُو ذَرٍّ النَّبِيَّ ﷺ فَذَكَرَ ذَلِكَ لَهُ فَقَالَ صَدَقَ أُبَيٌّ