As for the legal status of jama`ah (congregational) prayer, we would like to cite for you what the late Sheikh Sayyed Sabiq (may Allah bless his soul) says in his well-known book, Fiqh As-Sunnah:
Performing Prayer in congregation is sunnah mu’akkadah (confirmed sunnah). Many hadiths discuss the virtue and importance of performing prayer in congregation. Here are some of them:
Ibn `Umar quoted the Prophet (peace and blessings be upon him) as saying: “The reward of prayer performed in congregation outweighs that of the one 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 so
le intention of performing prayer. He does not take a step without being exalted in degree and having one of his sins forgiven. 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 prayer as long as he is waiting for it.” (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 (peace and blessings be upon him) 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 (peace and blessings be upon him) then said, “Then respond to it [by coming to the mosque]!” (Reported by Muslim)”
Thus, the view believed to be the most correct is that prayer in congregation is not obligatory, yet it is confirmed sunnah. However, it is a great loss for one to leave the congregational prayer in the mosque where one receives the great reward of 27 degrees and opts for performing prayer at home. And we should take the Prophet (peace and blessings be upon him) as an example. He never missed even a single congregational prayer. Even in his sickness, it was strenuous for him to walk; nonetheless, with the aid of two of his Companions he came (while his honorable feet were dragging on the ground) to the mosque and he prayed with the congregation.
Once the Prophet (peace and blessings be upon him) felt constrained to say:“I intend to tell the mu’adhin (caller to prayer) to say Allahu Akbar (Allah is the Greatest) and ask someone to lead the
prayer while I myself set to burn the houses of those who fail to attend the congregational prayer.” (Reported by Al-Bukhari & Muslim)
Here, the Prophet (peace and blessings be upon him) greatly condemned the act of those who do not attend the congregational prayer at the mosque, even though they perform it at home. One should ponder over this and take this as a warning against showing reluctance to attend the congregational prayer at the mosque.
Those who do not attend the congregational prayer in the mosque for silly reasons should know that the accursed Shaytan (Satan) tries to keep them away from prayer using all possible means to accomplish his goal. He first persuades them to neglect prayer in congregation, then to neglect tasbih (saying subhannallah, al-hamdulillah, and allahu-akbar each 33 times after each prayer along with other supplications), finally to neglect prayer all together.
How can they allow themselves to lose the reward of 27 degrees, sufficing with one degree only!! Have they reached a state that they are in no need of hasanat (good deeds) from Allah?
One can miss jama`ah prayer in the masjid for good reasons such as heavy rains, illness, sheer darkness and the like, but not for being a little bit tired or busy. A Muslim is supposed to rush to the Masjid whenever he hears the adhan.