What is the ruling of Islamic law regarding one who accuses Sheikh Muhammad Al-Hassan Ould Al-Diddew of corrupt belief and lying, and what is the view on those who defame scholars?

Shaykh, the erudite Muhammad al-Hassan al-Dido, is one of the Sunni scholars, and many scholars have attested to his merit and praised him. Accusing him of corrupting belief is strange, for he has expounded important books on sound doctrine, such as Kitab al-Tawhid and the erudite Muhammad Salim's poem on doctrine. He also has lectures on the Names and Attributes, and on loyalty and disavowal. Error is possible from scholars, and it should not be a reason to disparage or backbite a scholar. Rather, the means of reform is to discuss with the scholar using legitimate evidence.