Sunan Abi Dawud 4682
سنن أبي داود#4682Sahihحَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " أَكْمَلُ الْمُؤْمِنِينَ إِيمَانًا أَحْسَنُهُمْ خُلُقًا " .
Narrated AbuHurayrah: The Prophet (ﷺ) said: The most perfect believer in respect of faith is he who is best of them in manners
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-AlbaniHasan Sahih
Muhammad Muhyi Al-Din Abdul HamidHasan Sahih
Shuaib Al ArnautHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 42:87