Prayer: Congregational Prayers for the Obsessively Doubtful Person (Muwaswis)
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1385
If a person is so obsessively doubtful (muwaswis) in prayers that it invalidates his prayers, and if he becomes free of doubt only when he performs his prayers in congregation, he must perform his prayers in congregation.