The Book of the Merits of the Companions
حَدَّثَنِي أَبُو جَعْفَرٍ، مُحَمَّدُ بْنُ الصَّبَّاحِ حَدَّثَنَا حَفْصُ بْنُ غِيَاثٍ، حَدَّثَنَا عَاصِمٌ الأَحْوَلُ، قَالَ قِيلَ لأَنَسِ بْنِ مَالِكٍ بَلَغَكَ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لاَ حِلْفَ فِي الإِسْلاَمِ " . فَقَالَ أَنَسٌ قَدْ حَالَفَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ قُرَيْشٍ وَالأَنْصَارِ فِي دَارِهِ .It was said to Anas b. Malik:You must have heard this that Allah's Messenger (ﷺ) said: There is no alliance (hilf) of brotherhood in Islam. Anas said: Allah's Messenger (ﷺ) established the bond of fraternity between the Quraish and the Ansar in his home
From Sahih Muslim, whose reports the scholars accept as authentic.