Book 21, Hadith 164

It was narrated that Abu Umamah bin Sahi said:"A woman from among the people of Al-'Awali fell sick and the Prophet was the best in visiting the sick. He said: 'When she dies, inform me.' She died at night and they buried her without telling the Prophet. The following morning he asked about her and they said: we did not like to wake you, O Messenger of Allah.' So he went to her grave and offered the funeral prayer for her and said Takbir four times