The Messenger of Allah ﷺ said, "No people rise from a gathering in which they did not remember Allah without it being as though they had risen from the carcass of a donkey, and it will be a source of regret for them."
حدثنا محمد بن الصباح البزاز حدثنا إسمعيل بن زكريا عن سهيل بن أبي صالح عن أبيه
قال رسول الله ﷺ ما من قوم يقومون من مجلس لا يذكرون الله فيه إلا قاموا عن مثل جيفة حمار وكان لهم حسرة
Its isnad is sahih. Ahmad reported it in 2:389, and Nasai in Kubra, no. 10241, and Amal al-Yawm wal-Layla, no. 408, from the hadith of Suhayl, transmitted through him. Hakim graded it sahih according to the standard of Muslim, in 1:492, and Dhahabi agreed with him.