مُسْتَفَادًا مِنَ الْخَبَرِ الصَّادِقِ، جَعَلُوهُ سَبَبًا آخَرَ
Something derived from truthful report was treated as another cause.
When classifying sources of knowledge, one asks what ultimately warrants a claim. A conclusion may depend on reliable testimony even when further scholarly reasoning is involved.
For instance, a legal principle may be known through an authenticated report and then applied to a specific case through inference. The report supplies a premise, while reason performs the inference. Naming these activities separately does not establish two entirely new basic sources.
We must distinguish a source of information from a way of deriving a conclusion from that information.