All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

Islam has allowed joining prayers as a concession in some situations, such as travel, rain and fear. Some scholars have also allowed that for the sick who face hardship in offering prayers on their prescribed times. It was narrated from Ibn 'Abbas that the Prophet (PBUH) used to pray in Al-Madinah combining two prayer. Joining Zuhr and 'Asr, and Maghrib and 'Isha', when there was no fear nor rain. It was said to him: "Why?" He said: "So that there would not be any hardship on his Ummah."

Joining Maghrib and `Isha` at the times mosques are closed because of the pandemic isn`t valid, because there is no sound Sharia reason permitting that. It is the duty of every Muslim to offer prayers on their prescribed times since Allah the Almighty says {What means}: " When ye pass (Congregational) prayers, celebrate God’s praises, standing, sitting down, or lying down on your sides; but when ye are free from danger, set up Regular Prayers: For such prayers are enjoined on believers at stated times." {An-Nisa`, 103}. Another evidence is that Ibn Mas'ud said: I asked the Prophet which action is dearest to God and he replied, “Prayer at its proper time.” I asked what came next, and he replied that it was kindness to parents. I asked what came next and he replied that it was jihad in God's path. He said, “He told me of them, and if I had asked for more he would have told me more.” {Related by Bukhari}.

In principle, each prayer must be performed on its prescribed time, so joining prayers is only a concession. It is well known among jurists that analogy can't be applied based on concessions. Thus, it isn`t permissible to apply analogy to a new matter that hasn`t been addressed in Sharia, even if it involves greater difficulty. Just as it isn`t permissible to join prayers because of severe dust and heat, it isn`t permissible to join them because of the curfew. This is particularly since the wisdom behind combining prayers is relieving the prayer performers from going back to the mosque for the second prayer (Asr/`Isha`), and, in principle, at the time of curfew, this isn`t possible. 

At times of curfew, it is permissible to offer prayers in congregation at home and receive, Inshallah, the full reward of the congregation. In addition, if a Muslim prays alone, with a valid excuse, he is granted the reward of praying with the congregation. This is because the Messenger of Allah (PBUH) said, "When a slave of Allah suffers from illness or sets on a journey, he is credited with the equal of whatever good works he used to do when he was healthy or at home" [Al-Bukhari]. And Allah the Almighty knows best.