Sayyiduna Abu Umamah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "When some people sit in a gathering and then rise from that gathering without remembering Allah Almighty and without sending blessings upon the Prophet (peace and blessings be upon him), it (that is, this deed) will be a cause of loss (that is, of regret) for them."
Tabarani recorded it, and its narrators have been declared trustworthy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 16787
Hadith Gradingمحدثین:إسنادہ حسن
Hadith Takhrij«اخرجه الطبراني فى المعجم الصغير (974) اخرجه الطبراني فى المعجم الكبير (7751) ، أخرجه المعجم الكبير للطبراني برقم: 7751»