Mishkat al-Masabih 4 Prayer كتاب الصلاة 64

وَعَنْ عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صلى الله عَلَيْهِ وَسلم: «مَنْ صَلَّى الْعِشَاءَ فِي جَمَاعَةٍ فَكَأَنَّمَا قَامَ نِصْفَ اللَّيْلِ وَمَنْ صَلَّى الصُّبْحَ فِي جَمَاعَةٍ فَكَأَنَّمَا صَلَّى اللَّيْل كُله» . رَوَاهُ مُسلم

‘Uthman reported God’s Messenger as saying, “If anyone prays the evening prayer in company, it is as though he had remained awake in prayer half the night; but if anyone prays the Morning Prayer in company, it is as though he had prayed the whole night.” Muslim transmitted it.