العلم الضروري في المتواتر هو العلم بكونه خبر الرسول
In a mass-transmitted report, what is known necessarily is that it is a report of the messenger.
Certainty that a statement was conveyed by the Prophet and certainty that its content is true answer different questions. Tawātur may establish attribution; verified prophethood grounds acceptance of the authenticated message.
This resolves an apparent contradiction between describing prophetic report as inferential knowledge and attributing necessary knowledge to mass transmission. Provenance and truth of content are not the same epistemic claim.