Muslim scholars see that congregational prayer is a confirmed Sunnah. 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)
One person with the imam would constitute a congregation (jama`ah) even if the other person is a child or a woman. So, praying at home with one’s wife and children is regarded as salat jama`ah. However, it is commendable for a Muslim man to be accustomed to offer the obligatory Prayers in the mosque and to habituate his children to do that. It is also commendable if he offered nafl Prayers such as tahajjud and witr in congregation along with his wife and children at home. 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 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)
Elaborating more on the minimum number required for congregational Prayer, we cite what Sheikh Sayyed Sabiq states in his well-known book, Fiqh Us-Sunnah:
“One person with the imam constitutes a congregation even if the other person is a child or a woman.
Ibn `Abbas says: “I stayed with my Aunt Maymunah and the Prophet (peace and blessings be upon him) got up to pray during the night. I got up to pray with him and stood on his left and the Prophet took me by my hand and put me on his right side.”
Sa`id and Abu Hurayrah both reported that the Prophet (peace and blessings be upon him) said: “Whoever gets up during the night and wakes up his spouse and they pray two rak`ahs together, they both will be recorded among those (men and women) who remember Allah much.” (Abu Dawud)
Abu Sa`id narrates that a man entered the mosque, and the Prophet and his companions had already prayed. The Prophet (peace and blessings be upon him) said: “Who will give charity to him by praying with him?” So, a man from the people stood and prayed with him. (Ahmad, Abu Dawud, and at-Tirmidhi) Ibn Abi Shaybah relates that it was Abu Bakr who stood and prayed with the man.