A Black woman, or perhaps a man, used to sweep the mosque. The Prophet ﷺ noticed her absence and asked about her. He was told that she had died.He said, "Why did you not inform me?"Then he said, "Show me her grave."They showed him the grave, and he prayed over her.
حدثنا سليمان بن حرب ومسدد قالا حدثنا حماد عن ثابت عن أبي رافع
أن امرأة سوداء أو رجلا كان يقم المسجد ففقده النبي ﷺ فسأل عنه فقيل مات فقال ألا آذنتموني به قال دلوني على قبره فدلوه فصلى عليه
Bukhari narrated it in the Book of Prayer, chapter on sweeping the masjid and picking up rags, dirt, and sticks, no. 458, from Sulayman bin Harb, and Muslim narrated it in the Book of Funerals, chapter on praying over the grave, no. 956, through the hadith of Hammad bin Zayd, with the same wording.