Sunan Abi Dawud 3594
سنن أبي داود#3594SahihNarrated AbuHurayrah: The Prophet (ﷺ) said: Conciliation between Muslims is permissible. The narrator Ahmad added in his version: "except the conciliation which makes lawful unlawful and unlawful lawful." Sulayman ibn Dawud added: The Messenger of Allah (ﷺ) said: Muslims are on (i.e. stick to) their conditions
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniHasan Sahih
Muhammad Muhyi Al-Din Abdul HamidHasan Sahih
Shuaib Al ArnautHasan Sahih
Zubair Ali ZaiIsnaad Hasan
In-book reference: 25:24