Sunan Abi Dawud 5156
سنن أبي داود#5156Sahihحَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، وَعُثْمَانُ بْنُ أَبِي شَيْبَةَ، قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ الْفُضَيْلِ، عَنْ مُغِيرَةَ، عَنْ أُمِّ مُوسَى، عَنْ عَلِيٍّ، عَلَيْهِ السَّلاَمُ قَالَ كَانَ آخِرُ كَلاَمِ رَسُولِ اللَّهِ صلى الله عليه وسلم " الصَّلاَةَ الصَّلاَةَ اتَّقُوا اللَّهَ فِيمَا مَلَكَتْ أَيْمَانُكُمْ " .
Narrated Ali ibn AbuTalib: The last words which the Messenger of Allah (ﷺ) spoke were: Prayer, prayer; fear Allah about those whom your right hands possess
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih Lighairihi
In-book reference: 43:384