Hadithcore
Sahih Muslim, 1113 b
sahih

This hadith is narrated on the authority of Zuhri with the same chain of transmitters. Yahya (one of the narrators) said that Sufyan (the narrator) had stated:

I do not know whose statement it is:" It is the last word of the Messenger of Allah (ﷺ) which is accepted as (final as it abrogates the previous ones)."

حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، وَأَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ وَعَمْرٌو النَّاقِدُ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ عَنْ سُفْيَانَ، عَنِ الزُّهْرِيِّ، بِهَذَا الإِسْنَادِ ‏.‏ مِثْلَهُ ‏.‏ قَالَ يَحْيَى قَالَ سُفْيَانُ لاَ أَدْرِي مِنْ قَوْلِ مَنْ هُوَ يَعْنِي وَكَانَ يُؤْخَذُ بِالآخِرِ مِنْ قَوْلِ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏

References2 variants
In-Book Reference
Book 13, Hadith 111
USC-MSA web (English) reference
Book 6, Hadith 2467 (deprecated numbering scheme)