The phrase «عدلًا كان أو فاسقًا» requires careful framing. It concerns the working acceptance of information in everyday non-adversarial dealings. It is not a declaration that a dishonest person has binding evidentiary authority in every setting.
An ordinary commercial offer does not demand the full formal testimony procedure. But if that same speaker advances a contested claim to someone else’s property in court, the second category and its requirements arise.
The decisive change is not merely who speaks; it is the legal setting and the consequence for other people’s rights. Every case must be classified by that setting.