Prayer validity and congregational merit are separate issues. A correctly performed individual obligatory prayer does not automatically become invalid solely because no congregation was joined. Neglecting an emphasized communal practice is a distinct legal matter.
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Validity of Prayer and Reward for Congregation
Congregational Prayer: Its Status, Priority in Leading, and Conduct of the Imam
Prayer validity and congregational merit are separate issues. A correctly performed individual obligatory prayer does not automatically become invalid solely because no congregation was joined. Neglecting an emphasized communal practice is a distinct legal matter.