The caliphate of prophethood is thirty years

It is narrated from Abdullah bin Muhammad bin Aqil that he said: I heard (Muhammad) Ibn al-Hanafiyyah, at the beginning of the year in which he passed away (that is, the year 81 AH), say: "I am now sixty-five years old; I have passed the age of my father, for when my father passed away he was sixty-three years old." And Ibn al-Hanafiyyah passed away in that same year.
Imam al-Hakim said: As for the duration of the caliphate of the Commander of the Faithful Sayyiduna Ali (may Allah be pleased with him), it is according to what the Prophet (peace and blessings be upon him) decreed:

It is narrated from Sayyiduna Safinah Abu Abd al-Rahman (may Allah be pleased with him), the freed slave of the Messenger of Allah (peace and blessings be upon him), that the Prophet (peace and blessings be upon him) said: "The caliphate of Prophethood will last thirty years." Sa'id says: Count it up (the duration of the caliphates): the caliphate of Sayyiduna Abu Bakr was two years, that of Sayyiduna Umar bin al-Khattab ten years, that of Sayyiduna Uthman bin Affan twelve years, and the caliphate of Sayyiduna Ali comes to six years.

It is narrated from Sa'sa'ah bin Suhan that when Ibn Muljam made the murderous attack on Sayyiduna Ali (may Allah be pleased with him), he addressed us, and we said: O Commander of the Faithful! Appoint a successor over us. He said: "I am leaving you in the same state in which the Messenger of Allah (peace and blessings be upon him) left us." We had (earlier) said: O Messenger of Allah! Appoint a successor over us, and he (peace and blessings be upon him) had said: "If Allah knows good in you, He will appoint the best of you as ruler over you." Sayyiduna Ali (may Allah be pleased with him) said: "So Allah saw good in us and made Sayyiduna Abu Bakr (may Allah be pleased with him) our leader."