Congregational Prayer: Is it Mandatory?
As regards the question, Muslim scholars see that congregational prayer is a confirmed Sunnah.
In his well-known book, Fiqh As-Sunnah, the late Sheikh Sayyed Sabiq states:
“Performing salah in congregation is Sunnah Mu’akkadah, or a confirmed Sunnah. Many hadiths discuss the virtue and importance of performing salah in congregation. Here are some of them:
Ibn `Umar quoted the Prophet (peace and blessings be upon him) as saying: “The reward of salah performed congregation outweighs that of salah performed individually by twenty-seven degrees.” (Reported by Al-Bukhari and Muslim)
Abu Hurayrah quoted the Prophet (peace and blessings be upon him) as saying: “The prayer of a man in congregation is twenty-five times more superior (in reward) to his prayer in his house or the market – and this is because he makes the wudu’ (ablution) and perfects it, and goes to the mosque with the sole intention of performing salah. He does not take a step without being exalted in degree and having one of his sins obliterated. When he prays, as long as his wudu’ is still valid, the angels continue to pray [for him]: ‘O Allah, bless him. O Allah, bestow Mercy on him.’ He is considered as if he is performing salah as long as he is waiting for the salah.” (Reported by Al-Bukhari and Muslim)
Abu Hurayrah also reported that a blind man said to the Prophet, “O Messenger of Allah, I have no one to guide me to the mosque.” He asked the Prophet (peace and blessings be upon him) for permission to pray in his house, and the Prophet gave it to him. Then, when he turned to go, the Prophet called him and asked: “Do you hear the adhan (call to prayer)?” The blind man said, “Yes.” The Prophet then said: “Then respond to it [by coming to the mosque.]!” (Reported by Muslim)”