It is narrated from Abdur Rahman bin Harmalah that the Messenger of Allah ﷺ said: "The distinction between us and the hypocrites is attending the congregational prayer of Isha and Fajr. (Because) they do not have the ability to attend these two (prayers in congregation)."
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 275
Hadith Takhrijاسنادہ ضعیف لاعضالہ، اخرجہ البیہقی فی المعرفة السنن والآثار: 1427، ومالک فی الموطأ، الصلاة، باب ماجاء فی العتمة والصبح۔