Sunan Abi Dawud 4877
سنن أبي داود#4877Da'ifNarrated AbuHurayrah: The Prophet (ﷺ) said: The gravest sin is going to lengths in talking unjustly against a Muslim's honour, and it is a major sin to abuse twice for abusing once
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniDaif
Muhammad Muhyi Al-Din Abdul HamidDaif
Zubair Ali ZaiDaif
In-book reference: 43:105