Hadith: The reward of a prayer performed in congregation is twenty five times greater than that of a prayer performed by anyone of you alone. The angels of the night and the angels of the day gather at the Fajr prayer

عن أبي هريرة رضي الله عنه قال: سمعت رسول الله صلى الله عليه وسلم يقول: «تفضل صلاة الجميع صلاة أحدكم وحده، بخمس وعشرين جزءا، وتجتمع ملائكة الليل وملائكة النهار في صلاة الفجر» ثم يقول أبو هريرة: فاقرءوا إن شئتم: ﴿إن قرآن الفجر كان مشهودا﴾ [الإسراء: 78].
[صحيح] - [متفق عليه]

Abu Hurayrah (may Allah be pleased with him) reported: I heard the Messenger of Allah (may Allah’s peace and blessings be upon him) say: "The reward of a prayer performed in congregation is twenty five times greater than that of a prayer performed by anyone of you alone. The angels of the night and the angels of the day gather at the Fajr prayer." Then, Abu Hurayrah (may Allah be pleased with him) added: "Recite if you wish: {Indeed, the recitation of dawn is ever witnessed.} [Sūrat al-Isrā': 78]"
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

This Hadīth indicates that a prayer in congregation is twenty five times better and greater than a prayer offered individually. Then, it mentions that the angels of the night and the angels of the day assemble during the Fajr prayer. Thereafter, Abu Hurayrah (may Allah be pleased with him) cited in support of this meaning the verse that says: {Indeed, the recitation of dawn is ever witnessed} [Sūrat al-Isrā': 78]. In other words, the Fajr prayer is witnessed and attended by the angels of the day and the angels of the night. It is referred to as Qur’an here because it is Sunnah to prolong the recitation of the Qur’an therein more than in other prayers, and given the merit of its Qur’an’s recitation, which is witnessed by Allah, the Almighty, and the angels of the night and the angels of the day.