Imam Hussein, in one of his speeches, mentioned some important points to remind people why they needed to fight against the despotic governors and why he and his family deserved to be the rulers. Some of the points mentioned were:
1. The brotherhood of Prophet Muhammad and Imam Ali, as mentioned by Prophet Muhammad in the meeting he had with his companions and followers.
2. The decree of Prophet Muhammad, as ordained by God, to close the doors of all houses opening to Masjud-al-Nabi (The Mosque of the Prophet) except that of Imam Ali’s house.
3. Prohibition of others from even opening a window to the mosque.
5. During the Tabouk war, Prophet Muhammad told Imam Ali, “To me, you are like Aaron to Muses. You are my brother, as much as Aaron was Muses’ brother. And you are the ruler of the Muslims.”
6. The event of Mubahilah in which Prophet Muhammad took the dearest ones, his household, with him.
8. Regarding the Chapter Bara’a (Deliverance or Disavowal), Prophet Muhammad said that he would be no one, but myself or a man like himself.
9. Prophet Muhammad had so much trust in Imam Ali that he would ask for his help in case of problems.
10. Prophet Muhammad told Imam Ali, “Ali! You are from my blood, and I am from your blood. You will be the guardian of all the people after me.”
11. Prophet Muhammad also used to teach Imam Ali everything he knew.
12. Prophet Muhammad told his daughter, Fatimah, “Your husband is the best person I know, the first to embrace Islam, the greatest in patience and the most knowledgeable one of all.” By saying this, he inferred that Imam Ali was even greater than Jafar and Hamza.
13. Prophet Muhammad said, “I am the leader of the children of Adam. And my brother Ali is the leader of Arabs. Fatemeh is the best among the women in Heaven, and my grandsons, Hassan and Hussein are the best ones among the young people in Heaven.”
14. Prophet Muhammad commanded Imam Ali to help him take a bath and said that Gabriel would aid him.
15.Prophet Muhammad said to the people in his last lecture, “I will leave two very precious things among you; The Book of God and my Househol. Hold fast to them so that you won’t be misguided.” Then he continued, “If someone thinks that he likes me and does not like Ali, he is lying. No one likes me who dislikes Ali.” When someone asked Prophet Muhammad for his reason, he replied, “Because Ali is from my blood and I am from his blood. Whoever likes him, likes me and whoever likes me loves God. If someone dislikes Ali, he actually dislikes me and the one who dislikes me, does not like God either.”
source : http://www.tebyan.net