ما الأحاديث الصحيحة الواردة عن النبي صلى الله عليه وسلم في التشهد الأخير؟

The question is unclear. However, if the intent is to ask about the established nature of the final tashahhud from the Prophet, peace and blessings be upon him, then it is indeed established, and its reported forms have been mentioned. It is legislated to invoke blessings upon the Prophet, peace and blessings be upon him, during it, and a group of scholars have considered this a pillar. It is also legislated to supplicate generally during it. Among the reported supplications is seeking refuge in Allah from four things: the torment of Hell, the torment of the grave, the trials of life and death, and the evil of the Antichrist (Al-Masih Ad-Dajjal). Also among the supplications are: "O Allah, I seek refuge in You from the torment of the grave..." and "O Allah, I have wronged myself greatly...". And among them as well: "O Allah, help me to remember You, to be grateful to You, and to worship You in the best manner."