The Messenger of Allah ﷺ said:Whoever prays ʿIshaʿ in congregation, it will be like spending half the night in prayer (qiyam) and whoever prays ʿIshaʿ and Fajr in congregation, it will be like spending the whole night in prayer.ʿ (Using translation from Aḥmad 491)
قَالَ رَسُولُ اللهِ ﷺ مَنْ صَلَّى الْعِشَاءَ فِي جَمَاعَةٍ كَانَ كَقِيَامِ نِصْفِ لَيْلَةٍ وَمَنْ صَلَّى الْفَجْرَ فِي جَمَاعَةٍ كَانَ كَقِيَامِ لَيْلَةٍ أُخْرَى