Is it valid or invalid to pray an obligatory prayer at home alone without a valid health excuse? Does one receive reward for it, even if less than for congregational prayer? And how can one understand the differing opinions of scholars on this, especially those who deem it valid while sinful?

The difference of opinion regarding the ruling on congregational prayer is well-known. Some say it is a confirmed Sunnah (definition), others say it is a communal obligation (fard kifayah), and still others say it is an individual obligation (fard ayn) upon free, adult men – and this is the relied-upon position in the Hanbali school of thought, and it is the sound view that we choose and issue fatwas based upon. Congregational prayer is not a condition for the validity of the prayer. Rather, the prayer of one who prays alone without an excuse, while being able to pray in congregation, is valid. However, he is sinful for abandoning an obligation, not because his prayer is invalid or unacceptable. The evidence for its obligation from the Book of Allah is His saying, the Most High: {And when you are among them and lead them in prayer, let a group of them stand with you}. And from the Sunnah is the saying of the Prophet, peace and blessings be upon him: "Prayer in congregation is twenty-seven degrees better than prayer performed individually." This superiority indicates that individual prayer is valid and has merit, for if it were not valid, it would have no merit.