وَعَنْهُ قَالَ: قَالَ رَسُولُ اَللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ -«مَا قَعَدَ قَوْمٌ مَقْعَدًا لَمْ يَذْكُرُوا اَللَّهَ، وَلَمْ يُصَلُّوا عَلَى اَلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِلَّا كَانَ عَلَيْهِمْ حَسْرَةً يَوْمَ اَلْقِيَامَةِ»
“If people sit in an assembly in which they do not remember Allah or invoke blessings on the Prophet (sallallahu alayhi wa sallam) it will be a cause of grief to them on the Day of Resurrection.” Related by At-Tirmidhi who graded it as Hasan.
Bulugh al-Maram 1739, Book 16, The Comprehensive Book, Hadith 105. 1 min read