Mukhtasar Muslim (Abridged) 323 — Praying in congregation is among

‘Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with them both) says that we used to think that (in the time of the Messenger of Allah, peace and blessings be upon him) only that hypocrite would stay behind from the congregational prayer whose hypocrisy was evident, or a sick person. And even a sick person, if he could, would come by placing his hands on the shoulders of two men and join the prayer. And he said that the Messenger of Allah (peace and blessings be upon him) taught us matters of religion and guidance, and among those matters of guidance is to pray in a mosque where the call to prayer (adhan) is given.

Sayyiduna Abu Huraira (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: The prayer offered in congregation is superior by more than twenty degrees to the prayer offered at home or in the market, because when any one of you performs ablution well and goes to the mosque solely for the purpose of prayer, then for every step he takes towards the mosque, one rank is raised for him and one sin is erased. After entering the mosque, as long as he remains seated waiting for the prayer, he is considered to be in prayer, and the angels continue to supplicate for him as long as he remains seated at the place of prayer, as long as he does not harm the angels (by breaking his ablution). The angels keep saying: O Allah! Have mercy on him. O Allah! Forgive him. O Allah! Accept his repentance.