Is it incumbent upon a Muslim who has committed major disbelief (such as mocking Islam) to utter a different formulation of the Shahada? And is he required to add "He is alone without partner"? And is it obligatory to add "He is alone without partner" when reciting the Shahada in the Tashahhud and after ablution? And did the Prophet Muhammad add these words?

An apostate returns to Islam by uttering the two testimonies of faith: "I bear witness that there is no god but Allah, and that Muhammad is the Messenger of Allah," accompanied by sincere belief in the heart, acting upon their implications, and repenting from their apostasy by feeling remorse, abandoning the sin, and resolving never to return to it. The apostate may utter the two testimonies consecutively or separate them. Uttering "He is alone, without partner" is recommended but not obligatory.