Sunan Ibn Majah, Book 6, Hadith 1599 (In-Book) ⓘ
It was narrated from Ibn Buraidah from his father that the Prophet offered the funeral prayer for a deceased person after he had been buried.
حَدَّثَنَا مُحَمَّدُ بْنُ حُمَيْدٍ، حَدَّثَنَا مِهْرَانُ بْنُ أَبِي عُمَرَ، عَنْ أَبِي سِنَانٍ، عَنْ عَلْقَمَةَ بْنِ مَرْثَدٍ، عَنِ ابْنِ بُرَيْدَةَ، عَنْ أَبِيهِ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ صَلَّى عَلَى مَيِّتٍ بَعْدَ مَا دُفِنَ .
also referenced under: Hadith 1532 (Reference) & Volume 2, Book 6, Hadith 1532 (DarusSalam)