Are the statements of the Companions' scholars, such as Ibn Abbas, may Allah be pleased with them both, a definitive proof that cannot be opposed?

The situations concerning the saying of a Companion, according to scholars, fall into two categories:

The first category: The saying of a Companion that is not based on ijtihad (independent reasoning) but rather on narration (such as matters of the unseen). This type is given the ruling of being marfu' (attributed to the Prophet), unless there is a strong possibility that it originates from Isra'iliyyat (narrations from Jewish or Christian sources). In such a case, the rulings for Isra'iliyyat apply: belief if it conforms to Islamic law, rejection if it contradicts it, and withholding judgment if nothing is established.

The second category: The saying of a Companion that is based on ijtihad and opinion, and it has four situations: 1. If it contradicts a legal text: The text is prioritized, and the Companion's saying is not acted upon. 2. If it is contradicted by another Companion: The saying of neither of them serves as proof, and their opinions are weighed against each other. 3. If it became well-known and no one was known to have rejected it: It is considered a proof by the majority of scholars (silent consensus). 4. If its widespread nature is not known, and no one is known to have rejected it: The majority of scholars still use it as a proof.