Jami` at-Tirmidhi 1352
جامع الترمذي#1352Sahihحَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ الْخَلاَّلُ، حَدَّثَنَا أَبُو عَامِرٍ الْعَقَدِيُّ، حَدَّثَنَا كَثِيرُ بْنُ عَبْدِ اللَّهِ بْنِ عَمْرِو بْنِ عَوْفٍ الْمُزَنِيُّ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " الصُّلْحُ جَائِزٌ بَيْنَ الْمُسْلِمِينَ إِلاَّ صُلْحًا حَرَّمَ حَلاَلاً أَوْ أَحَلَّ حَرَامًا وَالْمُسْلِمُونَ عَلَى شُرُوطِهِمْ إِلاَّ شَرْطًا حَرَّمَ حَلاَلاً أَوْ أَحَلَّ حَرَامًا " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
Kathir bin 'Amr bin 'Awf Al-Muzani narrated from his father, from his grandfather, that the Messenger of Allah (ﷺ) said:"Reconciliation is allowed among the Muslims, except for reconciliation that makes the lawful unlawful, or the unlawful lawful. And the Muslims will be held to their conditions, except the conditions that make the lawful unlawful, or the unlawful lawful
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:
In-book reference: 15:32