Once when Imam Ali Riza was passing by the city of Nishapur, his followers surrounded him and requested him to narrate a hadith. The Holy Imam narrated the following hadith which he had heard from his father and his father from his grandfather and he from his father in a regular order of son hearing from his father up to the first Imam who heard it from the Holy Prophet and he from the archangel Jibra’il and he from the Almighty Allah”Monotheism is My fortress. Whoever enters it will be saved from My wrath”. The Holy Imam moved forward and then paused and said,
“That is, Monotheism with its prerequisites is the Divine fortress and I myself am one of its pre-requisites”. (Biharul Anwar, vol. III)
Thus the Holy Imam established an inseparable link between Monotheism and Imamate just as it exists between a notor car and its wheels or between Prayers and ablutions. In other words without the support of Imamate the concept of Monotheism will not be complete. As long as Monotheism is discussed, Imamate will also be referred to in the discussions, and that Imamate will ever remain viable and effective.
Example: If a physician has asked his patient to take either an injection or a capsule, the patient will understand that the injection and the capsule contain the same ingredients and that s why both would be effective in curing the disease. The following hadith has also been quoted in the books of ahadith:
“The Imamate of Ali is a fortress and whoever enters it will be in safety”. (Tafsir Nuruth Thaqalayn; Safinatul Bihar)
Now it is worth considering that Monotheism means a fortress and Imamate of Imam Ali also means the same that is ;he protection from the wrath of Allah. This is one explanation of the close link between Monotheism and the Imamate.
Thus if we accept the Imamate of Imam Ali it is evident that he will lead us to Allah or if we seek the guidance of Allah, He will direct us to Imam Ali for guidance.