While the Prophet was returning from his last piligrimage to Medina, he received this revealation from Allah,at a place called Ghadir Khumm,commading the Prophet to read it to the people.
"O Prophet proclaim what has been revealed to you from your Lord, for if you do it not, you have not conveyed His message, and Allah will protect you from the (evil designs of) people," Surah Al Maida Chapter 5 V 67. Then the prophet told his People, the reason for this verse, is to Proclaim Ali as the Chaliphate after him. Immediately following the passing of the Prophet (SAW), his Sahabat, and his fathers in law, turned against Ali. The home of Fatima, daughter of the Prophet was burned down by the Sahabat, despite several narrations from the Prophet about Fatima, one of which is who ever upset Fatima, upset me and who ever upset me upset Allah.
This book gives you summarized Ahadiths from Sunnis and Shias determining the Caliphate. It shows why the Caliphate belongs to Ali,and his decendant using Sunni Ahadiths to prove so. This book differentiates between the beliefs of the Shias and the Sunnis, and uses verses from the Holy Quran and from several Ahadith books.