A negress (or a youth) used to sweep the mosque. The Prophet ﷺ missed him, and when he asked about him the people told him that he had died. He said: Why have you not informed me ? He said: Lead me to his grave. So they led him and he prayed over him.  

أَنَّ امْرَأَةً سَوْدَاءَ أَوْ رَجُلاً كَانَ يَقُمُّ الْمَسْجِدَ فَفَقَدَهُ النَّبِيُّ ﷺ فَسَأَلَ عَنْهُ فَقِيلَ مَاتَ فَقَالَ أَلاَّ آذَنْتُمُونِي بِهِ قَالَ دُلُّونِي عَلَى قَبْرِهِ فَدَلُّوهُ فَصَلَّى عَلَيْهِ