Reference: Salīm, ʿAmr ʿAbul-Muniʿim (2006), al-Masāʾil al-ʿIlmiyyah wa al-Fatāwā al-Sharʿiyyah Fatāwā al-Shaykh al-ʿAllāmah Muḥammad Nāṣir al-Dīn al-Albānī fī al-Madīnah wa al-Imārāt, First Edition. Ṭanṭā: Dār al-Ḍiyāʾ.
Question: “Is supplication an obligation?”
Response: “Supplication in the general and absolute sense is obligatory and there are some supplications which are obligatory on certain occasions such as seeking refuge in Allāh from four – the punishment of Jahannam and the grave, the fitnah of life and death and the fitnah of the False Christ as mentioned in the ḥadīth of Bukhārī from Abū Hurayrah who said that the Messenger of Allāh said: “When one of you has completed the last tashahhud let him seek refuge in Allāh from four…” So in this there is a clear command for the praying person to seek refuge at the end of the prayer from these four things.”
This is why it has been reported from one of the Salaf, Ṭāwūs the noble Successor, that he commanded the one who did not seek refuge in Allāh from these four things to repeat the prayer.” [p. 167]