Allah’s true vicegerent is the Holy Prophet, for he is the first being to have been created, the most perfect manifestation of Allah’s Attributes and a collection of truth and Allah’s light:
The first thing Allah created was my light.[1]
Narrations say that the light of the Holy Prophet was created many thousand years before the creation of the universe. About the light of Imam `Al¢ (a.s), it has been said that he was together with the Holy Prophet in the invisible World. One of these lights became Prophet and the other became Imam. In this connection, the Holy Prophet says:
خُلِقْتُ أنَا وَعَلِيٌّ مِنْ نُورٍ وَاحِدٍ.
`Al¢ and I were created from the same light.[2]
Imam `Al¢ (a.s) who is Allah’s intimate friend is the heart of Allah’s Messenger as he shares with him everything except Prophethood. The Holy Prophet says:
آدَمُ وَمَنْ دُونَهُ تَحْتَ لِوَائِي يَوْمَ الْقِيَامَةِ؛ فَإذَا حَكَمَ اللهُ بَيْنَ الْعِبَادِ أخَذَ أمِيرُ الْمُؤْمِنِينَ اللِّوَاءَ.
Adam and others are under my banner on the Judgment Day. When Allah judges among His servants, Am¢r al-Mu’min¢n (i.e. Imam `Al¢) will hold the banner.[3]
Therefore; if the mission of all prophets led to the mission of the Holy Prophet, Imamate of all prophets is based on the Imamate of Imam `Al¢ who was with all prophets inwardly and with the Holy Prophet outwardly. Hence, the Imamate of Allah’s Messenger is united with the Imamate of `Al¢.
source : AHL AL-BAYT THE CELESTIAL BEINGS ON THE EARTH Allameh Hussein Ansariyan