The rationale classifies the described istisqa as a communal Muslim religious rite; therefore protected non-Muslims are not formally included in its prescribed assembly.
A distinction attributed to Malik permits them to go out independently to ask for rain without making them part of the Muslim ritual gathering. The issue is the structure of a specific rite, not a blanket ban on private appeals for rain.
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Salat al-Istisqa: Supplication for Rain and Juristic Rulings
The rationale classifies the described istisqa as a communal Muslim religious rite; therefore protected non-Muslims are not formally included in its prescribed assembly.
A distinction attributed to Malik permits them to go out independently to ask for rain without making them part of the Muslim ritual gathering. The issue is the structure of a specific rite, not a blanket ban on private appeals for rain.