Before closing this part, 1 think it advisablc to refer to some parts of the 77th Chapter of 'Yana-bi-ul-Mawaddah' (by Hafidh Sulaiman bin lbrahim Qanduzi Hanafi, died 1294 A.H.).
First he has quoted the famous Hadeeth that,
"'there would be Twelve Caliphs, all from Quraish."
From many books including Bukhari, Muslim, Abu Dawood and Tirmidhi.
Then he quotes many Traditions to the effect that The Holy Prophet said:
"I, Ali, Hassan, Hussain and nine from the descendants of Hussain are Pure and Sinless."
Also he quotes that The Holy Prophet told Imarn Hussain:
"Thou art Chief, son of Chief, brother of Chief; Thou art Imam, Son of Imam, brother of Imam; Thou art Proof (of God), son of Proof (of God), brother of Proof (of God), and father of nine Proofs (of God), nineth of whom would be Mahdi."
After quoting many such traditions he writes:
"Some scholars have said that the Traditions (which show that Caliphs after The Holy Prophet(saww) would be twelve) are famous, from many Asnaad (Chain). Now, with the passage of time and by the hisorical events, we know that by this Hadeeth The Holy Prophet meant the Twelve Imams from his Ahlul-Bait and Descendants, because:
This Hadeeth cannot fit the Four Khulafa Al-Rashideen from among his companions, as they were less than twelve. And it cannot fit on the Caliphs from the tribe of Umayya, because:
a) they were more than twelve;
b) all of them were tyrants and unjust (except Umar bin Abdul-Aziz); and
c) they were not from Bani Hashim and The Holy Prophet has said in a Hadeeth that
"all of them wil! be from sani Hashim .... "
And it cannot fit the Caliphs from Bani Abbas, because too:
a) they were more than twelve, and
b) they did (persecute the descendants of The Prophet and violate the injunction of the Quran in this respect.
Therefore the only way to interpret this Hadeeth is to accept that it refers to the twelve Imams from The Holy Prophet's Ahlul-Bait and Descendants, because they were, in their times, the most knowledgable, most illustrious, most God fearing, most pious, highest in their family lineage, best in personal virtues, and most honoured before Allah; and their knowledge was derived from their ancestor The Holy Prophet(saww), through their fathers, and by inheritance and by direct teaching from Allah.