Rank 4: ʿala shartihima without inclusion in either collection — a report outside both Sahih collections that genuinely meets both compilers’ authenticity conditions. This differs fundamentally from claiming the report was actually recorded in both books.
A list of shared narrator names is not sufficient. Each narrator’s transmission from the relevant teacher, report-specific precision, continuity, absence of anomalous conflict, and absence of disqualifying hidden defects need separate review. The words “on both compilers’ conditions” make a technical assertion requiring such evidence.
For example, a report in another compilation may have transmitters whose names occur in both Sahih collections. This alone does not establish rank four; it depends on the actual condition of the specific transmission.