The Book of the Merits of the Companions
وَحَدَّثَنِي حُسَيْنُ بْنُ حُرَيْثٍ، حَدَّثَنَا الْفَضْلُ بْنُ مُوسَى، عَنْ خُثَيْمِ بْنِ عِرَاكٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " أَسْلَمُ سَالَمَهَا اللَّهُ وَغِفَارُ غَفَرَ اللَّهُ لَهَا أَمَا إِنِّي لَمْ أَقُلْهَا وَلَكِنْ قَالَهَا اللَّهُ عَزَّ وَجَلَّ " .Abu Huraira reported Allah's Messenger (ﷺ) as saying:To the tribe of Aslam Allah has granted safety and to the tribe of Ghifar Allah has granted pardon. Verily it is not I that say this, but (it is) Allah the Exalted and Glorious. (who) says this
From Sahih Muslim, whose reports the scholars accept as authentic.