Sunan Ibn Majah, Volume 3, Book 22, Hadith 2698 (DarusSalam) ⓘ
It was narrated that 'Ali bin Abu Talib said: “The last words of the Prophet were: The prayer; and those whom your right hands prossess.”
حَدَّثَنَا سَهْلُ بْنُ أَبِي سَهْلٍ، حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، عَنْ مُغِيرَةَ، عَنْ أُمِّ مُوسَى، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، قَالَ كَانَ آخِرُ كَلاَمِ النَّبِيِّ صلى الله عليه وسلم " الصَّلاَةَ وَمَا مَلَكَتْ أَيْمَانُكُمْ " .
also referenced under: Hadith 2698 (Reference) & Book 22, Hadith 2802 (In-Book)