How authentic is the book Nahj al-Balagha?

It is not correct to attribute the book "Nahj al-Balagha" to Amir al-Mu'minin Ali ibn Abi Talib, may Allah be pleased with him, due to the lack of chains of transmission (isnad) for it, and because some of its content is false or fabricated. A number of scholars have pointed out the falsehoods within it, including Al-Dhahabi and Ibn Taymiyyah, who clarified that the author of the book omitted many narrators, and that most of its content did not exist before the book's appearance. Furthermore, it contains insults against the Companions, contradictions, and weak expressions that would not emanate from masters of eloquence. Additionally, its author is not among those qualified in narration. Therefore, it is not permissible to use what is stated therein as evidence in matters of Islamic law.