The maid of the mosque

There was an old black woman who cleaned the mosque in Madinah. She was a quiet, poor Muslim. When Hazrat Muhammad (pbuh) could not see her for a few days, she asked, "Where is she?" His friends told him that she had died and that they had buried her quietly. He got offended and said,

"Why did you not inform me?"

He went to her grave and led her janazah prayer again.