Is it permissible to deviate from the established Sunnah due to the opposition of the Rafidah, and what is the authenticity of what is stated in Ibn Taymiyyah's book "Minhaj al-Sunnah" that Uthman gathered the entire Qur'an while Ali did not memorize it completely, and that the hadith "The most just among you in judgment is Ali" is not authentic, and the hadith "I am the city of knowledge and Ali is its gate" is weak, despite evidence indicating otherwise?

Ibn Taymiyyah should not be prejudiced against for his discussion of the scholars' disagreement regarding Ali (may Allah be pleased with him) memorizing the Qur'an. He did not intend to denigrate him but rather discussed the preference of Ali over Uthman, relying on evidence. Nor was he the first to mention this disagreement. Whoever harbored ill thoughts about him has sinned, for Ibn Taymiyyah affirmed Ali's virtue and guardianship, considering him the master of every believer and the best of the Prophet's household after the Prophet (peace be upon him).

Regarding Ibn Taymiyyah's weakening of the hadith: "The best of you in judgment is Ali," the intention was not to deny Ali's merits, but rather to clarify what is authentic and what is not among the hadiths. This hadith was not sound according to him, and even if it were sound, it would not indicate his superiority over the Caliphs, because the same hadith mentions that Mu'adh ibn Jabal is the most knowledgeable of what is lawful and unlawful, and Zayd ibn Thabit is the most knowledgeable of the obligatory shares. Ibn Taymiyyah does not dispute Ali's virtue, knowledge, and precedence; rather, he refutes those who used this hadith to prefer him over the Caliphs.

As for the hadith: "I am the city of knowledge and Ali is its gate," it is weak. Scholars have differed regarding its authenticity. Al-Hafiz Ibn Hajar considered it hasan (good), not reaching the level of sahih (authentic) nor descending to the level of falsehood. It does not indicate that knowledge is confined to Ali, for the Tabi'un (followers) acquired knowledge from other Companions.

As for other issues, such as leveling graves and wearing rings on the right hand, Ibn Taymiyyah mentioned them in the context of his rebuttal against those who criticize the Sunnis, clarifying that the Imams of Islam believe that what is legislated should not be abandoned merely because people of innovation do it.