(72) باب كَنْسِ الْمَسْجِدِ وَالْتِقَاطِ الْخِرَقِ وَالْقَذَى وَالْعِيدَانِ
Narrated Abu Huraira:
A black man or a black woman used to sweep the mosque and he or she died. The Prophet (ﷺ) asked about her (or him). He was told that she (or he) had died. He said, "Why did you not inform me? Show me his grave (or her grave)." So he went to her (his) grave and offered her (his) funeral prayer."
Reference: Sahih al-Bukhari 458
In-book reference: Book 8, Hadith 106
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 8, Hadith 448