Sunan Abi Dawud 4855
سنن أبي داود#4855SahihNarrated AbuHurayrah: The Prophet (ﷺ) said: People who get up from an assembly in which they did not remember Allah will be just as if they had got up from an ass's corpse, and it will be a cause of grief to them
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 43:83