Arabic text
عَنْ أَبِي هُرَيْرَةَ رضي الله عنه قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ: «مَا مِنْ قَوْمٍ يَقُومُونَ مِنْ مَجْلِسٍ لَا يَذْكُرُونَ اللَّهَ فِيهِ إِلَّا قَامُوا عَنْ مِثْلِ جِيفَةِ حِمَارٍ، وَكَانَ لَهُمْ حَسْرَةً».
Translation
Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said: "No people leave a gathering in which they did not remember Allah except that it will be as if they are leaving the carcass of a donkey, and it will be a cause of regret for them."
Explanation
The Prophet (may Allah's peace and blessings be upon him) informed that no people attend a gathering then leave it without remembering Allah therein except that it will be as if they are leaving a gathering on the carcass of a donkey in terms of rottenness and filth because of being too preoccupied with their speech from remembering Allah. This gathering will be a source of their sorrow, loss, and eternal regret on the Day of Judgment.
Source: HadeethEnc.com