In the Name of Allah, the Compassionate, the Merciful.
Praise be to Allah the Lord of the worlds. Benedictions be upon Muhammad (s.a.w.s.) and his Purified Progeny. Peace be upon the righteous Companions.
Some of the controversial issues have divided the Muslims. These issues have been misused by the enemies of Islam to divide the Muslims and to weaken them. Therefore, in order to unite the Muslims and to defend the boundaries of Islam it is necessary to clear the misunderstandings regarding these  differences. In sorting out these issues we have been ordered to confine ourselves within some limits. As the Almighty Allah says: "And obey Allah and His Apostle and so not quarrel for then you will be weak in hearts and your power will depart..." (Sura Anfal 8 : 46)
It is a must for us today, and for all times to refer to Qur'an and Hadith in case of any difference of opinion. As the Almighty Allah says: "...then if you quarrel about anything, refer it to Allah and the Apostle..." (Sura Nisa 4 : 59)
In this series we shall refer to the Qur'an and Hadith to guide us on the correct path in various controversial topics. We seek the help of the Almighty in this.

Al-'Askari
Narrations of the Holy Prophet [s] Stipulating the Number of Imams
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The Messenger of Allah (s.a.w.s.) informed that the number of Imams after him are twelve, as the compilers of Sihah and Masanid have narrated it.

In Sahih of Muslim:
The Prophet (PBUH&HF) said: "The [Islamic] religion will continue until the Hour (day of resurrection), having twelve Caliphs for you, all of them will be from Quraysh."
Sahih Muslim (Arabic version) Kitab al-Imaara, 1980 Edition Pub. in Saudi Arabia, v3, p1453, Tradition #10

Sahih Muslim, (English version)
Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh),  v3, p1010, Tradition #4483 Hadith #3398 (numbering of al-'Alamiyyah)
The Prophet (PBUH&HF) said: "The affairs of people will continue to be conducted (well) as long as they are governed by the twelve men, all of them from Quraysh."

Sahih Muslim (Arabic version) Kitab al-Imaara, 1980 Edition Pub. in Saudi Arabia, v3, p1453, Tradition #6 Sahih Muslim, (English version) Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh),  v3, p1010, Tradition #4478 Hadith #3394 (numbering of al-'Alamiyyah)
Narrated Jabir ibn Samura: The Prophet (PBUH&HF) said: "This matter (life) will not end, until it is passed by twelve Caliphs." He then whispered a sentence. I asked my father what the Prophet said. He said, the Prophet added: "All of them will be from Quraysh."

Sahih Muslim (Arabic version) Kitab al-Imaara,1980 Edition Pub. in Saudi Arabia,
v3, p1452, Tradition #5 Sahih Muslim, (English version) Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh), v3, p1009, Tradition #4477 Hadith #3393 (numbering of al-'Alamiyyah) The Prophet (PBUH&HF) said: "Islam will continue to be triumphant until there have been twelve Caliphs, all of them from Quraysh."
Sahih Muslim (Arabic version) Kitab al-Imaara,1980 Edition Pub. in Saudi Arabia, v3, p1453, Tradition #7 Sahih Muslim, (English version)
Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh),  v3, p1010, Tradition #4479 Hadith #3395 (numbering of al-'Alamiyyah)
The Prophet (PBUH&HF) said: "Islam will continue to be triumphant until there have been twelve Caliphs, all of them from Quraysh."

Sahih Muslim (Arabic version)
Kitab al-Imaara,1980 Edition Pub. in Saudi Arabia, v3, p1453, Tradition #8
Sahih Muslim, (English version) Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh), v3, p1010, Tradition #4480

Hadith #3396 (numbering of al-'Alamiyyah)
The Prophet (PBUH&HF) said: "Islam will continue to be triumphant and protected until there have been twelve Caliphs, all of them from Quraysh."
Sahih Muslim (Arabic version) Kitab al-Imaara, 1980 Edition Pub. in Saudi Arabia, v3, p1453, Tradition #9
Sahih Muslim, (English version)
Chapter DCCLIV (titled: The People are subservient to the Quraysh and the Caliphate is the Right of the Quraysh), v3, p1010, Tradition #4481 Hadith #3397 (numbering of al-'Alamiyyah)

In Sunan of al-Tirmidhi:
The Prophet (PBUH&HF) said: "There will be after me twelve Amir (Prince/Ruler), all of them from Quraysh."
Sunan al-Tirmidhi (Arabic) Chapter of Fitan, 2:45, (India) and 4:501 Tradition # 2225 (Egypt)
Hadith #2149 (numbering of al-'Alamiyyah)
In Sunan of Abu Dawud: "This religion remains standing until there are twelve vicegerents over you, all of them agreeable to the nation, all of them from Quraysh."
Sunan Abu Dawud (Arabic)2:421, Kitab al-Mahdi.
Sunan Abu Dawud (Arabic)3:106, Kitab al-Mahdi.
Hadith #3731 (numbering of al-'Alamiyyah)
"The Prophet (PBUH&HF) said: "Islam will continue to be triumphant until there have been twelve Caliphs," So people said Takbir and made noise, then he said a light word I didn't hear. I [Jabir bin Samura] said to my father: What did he say? He said "All of them are from Quraysh."
Sunan Abu Dawud (Arabic) 2:241,, Kitab al-Mahdi.
Sunan Abu Dawud (Arabic)3:106, Kitab al-Mahdi.
Hadith #3732 (numbering of al-'Alamiyyah)

In Sahih of al-Bukhari:
Narrated Jabir ibn Samura: I heard the Prophet saying, "There will be twelve commanders (Amir)." He then said a sentence which I did not hear. My father said, the Prophet added, "All of them will be from Quraysh."
Sahih al-Bukhari (English)
Hadith: 9.329, Kitabul Ahkam.
Sahih al-Bukhari (Arabic, 4:165,  Kitabul Ahkam.
Hadith #6682 (numbering of al-'Alamiyyah)
These traditions are also narrated in other sources [1]

And in a tradition:
Then the Prophet (s.a.w.s.) spoke a few words which I could not understand. Then I asked my father: "What did the Messenger of Allah (s.a.w.s.) say?" He said: "All of them are from the Quraysh." [2]
And in another tradition: "The enmity of their enemies will not harm them." [3]
And in another tradition: "This nation will always remain straight in its affairs, and triumphant against the enemies, till twelve Caliphs will be among them; all of them from Quraysh. Then there will be discord and confusion." [4]
And in a tradition: "There will be twelve upright Imams for this nation. Those who try to disgrace them will not succeed; all of them shall be from the Quraysh."
"The affair of the people will continue as long as twelve men rule over them."
And from Anas: "This religion will remain till twelve Imams from Quraysh (will pass), then when they expire the earth will swallow its inhabitants." [5]
And in a tradition: "The affair of this nation will always be apparent till the twelve Imams will rise, all of them from the Quraysh." [6]
Ahmad and Al-Hakim and others have narrated similarly from Masrooq who said: "We were sitting one evening with Abdullah (ibn Mas'ud). We were reciting the Qur'an, then a man asked him: "O Abu Abdur-Rahman, did you ask the Messenger of Allah (s.a.w.s.) how many Caliphs will rule this nation?" Abdullah said: "No one asked me about this before you from the time I arrived in Iraq." He said: "We asked him (the Prophet s.a.w.s.), he said: "Twelve, (like) the number of the Chiefs of Bani Israel." [7]
And in a tradition:
Ibn Mas'ud said: "The Messenger of Allah (s.a.w.s.) said: "There will be Caliphs after me, whose number is like those of the companions of Musa." [8]
Ibn Kathir said: "And there is a similar narration from Abdullah bin 'Umar, Hudhayfah and Ibn 'Abbas. [9]
However, I have been unable to find this tradition of Ibn 'Abbas or others as reported by Al Hakim Al Haskani.
The traditions assert that the number of authorities are twelve and all of them are from Quraysh, and, Imam Ali (peace be upon him) clarified it in his speech that they shall be from the Quraysh when he said: "Surely Imams will be from the Quraysh, they have been planted in this line through Hashim. It would not suit others nor would others be suitable as heads of affairs." [10]
And he said: "O Allah! Yes, but the earth is never devoid of those who maintain Allah's plea either openly and reputedly or, being afraid, and hidden in order that Allah's pleas and proofs should not be rebutted." [11]

Notes:
[1] Muslim b. al-Hajjaj, Sahih, 3:1453, Tradition No. 1821, Kitabul Imarah. Al-Bukhari, Sahih, 4:165, Kitabul Ahkam. Al-Tirmidhi, Sunan, Chapter of Fitan, 2:45 (India) and 4:501 Tradition # 2225 (Egypt) Abu Dawud, Sunan, 3:106, Kitab al-Mahdi. Al-Tayalisi, Musnad, Tradition No. 767 and 1278. Ahmad b. Hanbal, Musnad, 5:86. Al-Muttaqi al-Hindi, Kanz al-'Ummal 13:26-27. Abu Nu'aym al-Isbahani, Hilyat al-'awliya' 4:333. Jabir bin Samurah bin Junada was the nephew of Sa'd bin Abi Waqqas. He died at Kufa. The compilers of traditions have narrated 146 traditions from him. For his biography, refer to Usd al-Ghaba or Taqrib al-Tahdhib.
[2] Ibn Hajar al-'Asqalani, Fath al-Bari 16:338. Al-Hakim al-Nisaburi, Mustadrak al-Sahihayn 3:167.
[3] Ibn Hajar al-'Asqalani, Fath al-Bari 16:338.
[4] Muntakhab Kanz al-'Ummal 5:321. Ibn Kathir, Ta'rikh, 6:249.Al-Suyuti, Tarikh al-Khulafa, Vol 10. Al-Muttaqi al-Hindi, Kanz al-'Ummal ,13:26. Ibn Hajar al-Haythami, Al-Sawa'iq al-Muhriqa Vol 28.
[5] Al-Muttaqi al-Hindi, Kanz al-'Ummal , 13:27
[6] Ibid.
[7] Ahmad b. Hanbal, Musnad, 1:398 and 406. Al-Hakim al-Nisaburi, Mustadrak , 4:501 Al-Dhahabi, Talkhis , 4:501. Ibn Hajar al-'Asqalani, Fath al-Bari 16:339. Ali b. Abu Bakr al-Haythami, Majma' al-Zawa'id 5:190. Ibn Hajar al-Haythami, Al-Sawa'iq al-Muhriqa, vol 12. Al-Suyuti, Tarikh al-Khulafa, Vol 10. Al-Suyuti or al-Tabarani], Jami' al-Saghir 1:75. Al-Muttaqi al-Hindi, Kanz al-'Ummal, 13:27.
[8] Ibn Kathir, Ta'rikh, 6:248. Al-Muttaqi al-Hindi, Kanz al-'Ummal, 13:27. Al-Haskani , Shawahid al-Tanzil, 1:455, Tradition No. 626.
[9] Ibn Kathir, Ta'rikh, 6:248.
[10] Imam 'Ali b. Abi Talib [a], Nahjul Balagha, Sermon no. 142.
[11] Shaykh Sulayman Qanduzi al-Hanafi, Yanabi' al-Mawaddah, p. 523.