فهو كدعوى الشيء ببينة
It resembles putting forward a claim together with an indication of its truth.
Kināyah may present a sign from which the hearer moves to the desired quality: the abundant ash is offered instead of directly saying “generous.” This lends the quality an evidential appearance in the discourse.
That is not necessarily formal logical or legal proof. It is a rhetorical way of strengthening an assertion, not a license to invent objective facts.