“The Messenger of Allah (ﷺ), Abu Bakr and ‘Umar did not give us so much leeway in anything as they did with regard to the prayer for the deceased,” meaning that there was nothing affixed.
Sunan Ibn Majah Book 6, Hadith 69
← Previous Hadith “I saw the Messenger of Allah (ﷺ) offering the funeral prayer for a man among the Ansar, and I heard him say: ‘Allahumma salli ‘alayhi waghfirlahu warhamhu, wa ‘afihi wa’fu ‘anhu, waghsilhu bi ma’in wa thaljin wa baradin, wa naqqihi min adh-dhunubi wal-khataya kama yunaqqath-thawbul-abyadu minad-danas, wa abdilhu bi darihi daran khayran min darihi, wa ahlan khayran min ahlili, wa qihi fitnatal-qabri wa ‘adhaban-nar. (O Allah, send blessing upon him, forgive him, have mercy on him, keep him safe and sound, and pardon him; wash him with water and snow and hail, and cleanse him of sins just as a white garment is cleansed of dirt. Give him in exchange for his house that is better than his house, and a family that is better than his family. Protect him from the trial of the grave and the torment of the Fire).’”

Sunan Ibn Majah Book 6, Hadith 68 Next Hadith → It was narrated from ‘Uthman bin ‘Affan that the Prophet (ﷺ) offered the funeral prayer for ‘Uthman bin Maz’un, and he said four Takbir over him.

Sunan Ibn Majah Book 6, Hadith 70