Riyad as-SalihinChapter 4Hadith 156
Full Sharh — Riyad as-Salihin 156
وعنه عن النبي صلى الله عليه وسلم قال: "ما جلس قوم مجلساً لم يذكروا الله تعالى فيه، ولم يصلوا على نبيهم فيه، إلا كان عليهم ترة؛ فإن شاء عذبهم، وإن شاء غفر لهم" ((رَوَاهُ التِّرمِذِيُّ وَقَالَ: "حَدِيثٌ حَسَنٌ")).
English Translation
Abu Hurairah (May Allah be pleased with him) reported:: The Prophet (ﷺ) said, "Whenever a group of people sit in a gathering in which they do not remember Allah the Exalted, nor supplicate to elevate the rank of their Prophet, such a gathering will be a cause of grief to them. If Allah wills, He will punish them, and if He wills He will forgive them.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of the Etiquette of Sleeping, Lying and Sitting etc
Hadith Number
156