Is supplicating for the Prophet (ﷺ) and seeking refuge from the torment of the grave, the torment of Hell, the trials of life and death, and the trial of the Antichrist obligatory during the Tashahhud, or is it Sunnah?

Scholars have unanimously affirmed the importance of seeking refuge with Allah from four things: the torment of Hell, the torment of the grave, the trials of life and death, and the trial of the Dajjal (Antichrist). This is based on what is narrated in Sahih Muslim, that the Prophet (peace be upon him) used to teach this to his Companions just as he would teach them a surah from the Qur'an. Scholars have differed regarding the ruling on this supplication for seeking refuge (isti'adha). The majority opinion is that it is recommended (mustahabb), while a group of scholars held that it is obligatory (wajib), citing the action of Tawus, who ordered his son to repeat his prayer because he had omitted this supplication. However, the more probable opinion is that it is recommended, and Tawus's action is to be understood as an emphasis on its recommendability specifically for his son.