Abu Huraira said that a negress (or a youth) used to sweep the mosque. Allah's Messenger ﷺ missed her, and when he asked about her (or him) the people told him he had died. He asked why they had not informed him, and it appeared as if they had treated her (or him) as of little account. He asked the people to lead him to the grave, and when they did so he prayed over her (The wording of this tradition causes some difficulty owing to the indefiniteness as to whether the person was a man or a woman. Sometimes the alternative is mentioned, as in the translation, but sometimes merely the masculine singular pronoun and at others merely the feminine singular pronoun is used) and then said, "These graves are full of darkness for their occupants, but Allah will illuminate them for them by reason of my prayer over them.” (Bukhari and Muslim, the wording being Muslim’s.)