From Sahih Muslim (Hadith 1333):
Ibn 'Abbas reported that the Messenger of Allah (ﷺ) used to teach them this supplication (in the same spirit) with which he used to teach them a surah of the Qur'an. He would thus instruct us:"Say, O Allah, we seek refuge with Thee from the torment of Hell. And I seek refuge with Thee from the torment of the grave, and I seek refuge with Thee from the trial of al-Masih ad-Dajjal, and I seek refuge with Thee from the trial of life and death." Muslim b. Hajjaj said: It has reached me that Tawus said to his son: Did you make this supplication in prayer? He said: No. (Upon this) he (Tawus) said: Repeat the prayer. Tawus has narrated this hadith through three or four (transmitters) with words to the same effect
Reference: Muslim 1333