Abu Huraira reported: A black woman, or a young man, used to maintain the mosque and one day the Messenger of Allah, peace and blessings be upon him, missed her and asked about her. They said, “She has died.” The Prophet said, “You would not announce it to me?” It was as if they considered her insignificant. The Prophet said, “Show me to her grave.” They led him to it and he prayed over her, then the Prophet said, “Verily, these graves are filled with darkness over their inhabitants. Allah Almighty illuminates them by my prayers over them.”
Source: Ṣaḥīḥ Muslim 956
Grade: Sahih (authentic) according to Muslim
عَنْ أَبِي هُرَيْرَةَ أَنَّ امْرَأَةً سَوْدَاءَ كَانَتْ تَقُمُّ الْمَسْجِدَ أَوْ شَابًّا فَفَقَدَهَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَسَأَلَ عَنْهَا فَقَالُوا مَاتَ قَالَ أَفَلَا كُنْتُمْ آذَنْتُمُونِي قَالَ فَكَأَنَّهُمْ صَغَّرُوا أَمْرَهَا فَقَالَ دُلُّونِي عَلَى قَبْرِهَا فَدَلُّوهُ فَصَلَّى عَلَيْهَا ثُمَّ قَالَ إِنَّ هَذِهِ الْقُبُورَ مَمْلُوءَةٌ ظُلْمَةً عَلَى أَهْلِهَا وَإِنَّ اللَّهَ عَزَّ وَجَلَّ يُنَوِّرُهَا لَهُمْ بِصَلَاتِي عَلَيْهِمْ
956 صحيح مسلم كتاب الجنائز باب الصلاة على القبر