English Translation
Narrated Abu Huraira: A black person, a male or a female used to clean the Mosque and then died. The Prophet (p.b.u.h) did not know about it . One day the Prophet remembered him and said, "What happened to that person?" The people replied, "O Allah's Apostle! He died." He said, "Why did you not inform me?" They said, "His story was so and so (i.e. regarded him as insignificant)." He said, "Show me his grave." He then went to his grave and offered the funeral prayer.
This hadith is from Sahih al-Bukhari, the most rigorously authenticated collection in Islamic scholarship. No editorial opinion is added.