It was narrated from Ibn Buraidah from his father that the Prophet (ﷺ) offered the funeral prayer for a deceased person after he had been buried.
Sunan Ibn Majah Book 6, Hadith 100
← Previous Hadith It was narrated from Anas that the Prophet (ﷺ) offered the funeral prayer at a grave after the burial.

Sunan Ibn Majah Book 6, Hadith 99 Next Hadith → “There was a black woman who used to sweep the mosque, and she passed away at night. The following morning the Messenger of Allah (ﷺ) was told of her death. He said: ‘Why did you not call me?’ Then he went out with his Companions and stood at her grave, and said Takbir over her, with the people behind him, and he supplicated for her, then he went away.’”

Sunan Ibn Majah Book 6, Hadith 101