Do the verses and narrations interpret that ruling by other than what Allah has revealed is kufr (disbelief), and what is the authenticity of the narration from Ibn Abbas: "kufr (disbelief) lesser than kufr"?

In summary, Ibn Mas'ud's narration was attributed by Al-Busiri and Al-Mundhiri to Al-Tabarani as mawquf (stopped at a Companion) with an authentic chain of transmission. Al-Haythami, in Majma' Al-Zawa'id, attributed it to Al-Tabarani in Al-Kabeer, stating that its narrators are those of the Sahih. Al-Albani said: "Authentic li ghayrihi (due to external corroboration), mawquf." As for Ibn 'Abbas's narration, it is authentically reported from him through various chains and wordings, and can be referred to in Shaykh Al-Albani's Silsilat Al-Ahadith Al-Sahiha.

Regarding the implication of the narration and the verses, scholars of tafsir differed on the meaning of "disbelief" in His (Allah's) saying: "And whoever does not judge by what Allah has revealed – then it is those who are the disbelievers." Al-Tabari favored the view that these verses were revealed concerning the disbelievers among the People of the Book who rejected Allah's judgment, and that they encompass anyone who does not judge by what Allah has revealed while rejecting it.

The verified opinion among scholars is that judging by other than what Allah has revealed is categorized into: - Major disbelief (kufr akbar) that expels one from the fold of Islam: This occurs if the ruler deems it lawful or believes that judging by what Allah has revealed is not obligatory, despite being certain that it is Allah's judgment. - Minor disbelief (kufr asghar) (not expelling one from the fold of Islam): This occurs if one believes in the obligation of judging by what Allah has revealed, but deviates from it due to disobedience and personal desire, while acknowledging the sin. - As for one who strives to reach a correct judgment (ijtihad) and errs, he receives a reward for his ijtihad, and his error is forgiven.

This is the view supported by Shaykh Al-Islam Ibn Taymiyyah, Ibn Al-Qayyim, and Shaykh Ibn Baz, who differentiated between the denier who deems it lawful and the disobedient person who acknowledges his sin.