ولا بد أن تكون المقدمات المستعملة فيها مقنعة للسامعين، مفيدة للواعظين.
The premises used should be persuasive to listeners and useful to those offering exhortation or guidance.
Persuasive to listeners means that listeners understand the claims and have some intelligible reason to accept them. Unfamiliar technical terms or unrelated assertions may fail to persuade.
A sound rhetorical presentation therefore requires more than forceful delivery or emotion: its premises should be comprehensible, acceptable in context and appropriately connected to the conclusion.