It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Prophet of Allah (peace and blessings be upon him) said on the day of Khaybar: "I shall certainly send (to fight) a man whom Allah will never disgrace." Then he (peace and blessings be upon him) sent for Sayyiduna Ali (may Allah be pleased with him) while he was grinding flour by the saddles, and (at that time) none of you would grind flour. The people brought him while his eyes were sore. He said: "O Prophet of Allah! I can hardly see anything." So he (peace and blessings be upon him) blew with his saliva into both his eyes, waved the banner three times, then handed it to him. Victory was granted at his hands, and he brought Sayyidah Safiyyah bint Huyayy (may Allah be pleased with her) (with him).
He narrated: Then he (peace and blessings be upon him) said to his cousins: "Which of you will be my wali (helper and loyal friend) in this world and the Hereafter?" He (peace and blessings be upon him) asked each man among them in turn: "O so-and-so! Will you be my wali in this world and the Hereafter?" Three times (it happened so), and each one would say: "No." Until he (peace and blessings be upon him) reached the last of them, and Sayyiduna Ali (may Allah be pleased with him) said: "O Prophet of Allah! I am your wali in this world and the Hereafter." So the Prophet (peace and blessings be upon him) said: "You are my wali in this world and the Hereafter."
He narrated: He (peace and blessings be upon him) sent Sayyiduna Abu Bakr (may Allah be pleased with him) with Surah al-Tawbah, then sent Sayyiduna Ali (may Allah be pleased with him) after him. Sayyiduna Abu Bakr (may Allah be pleased with him) asked: "O Ali! Perhaps Allah and His Messenger have become displeased with me?" Sayyiduna Ali (may Allah be pleased with him) replied: "No, but the Prophet of Allah (peace and blessings be upon him) said: 'It is not fitting that anyone convey (the message) on my behalf except a man who is from me and I am from him.'"
He narrated: The Messenger of Allah (peace and blessings be upon him) placed his cloak over Sayyiduna Ali, Sayyidah Fatimah, Sayyiduna al-Hasan and Sayyiduna al-Husayn (may Allah be pleased with them), then said: "Allah only intends to remove impurity from you, O people of the household, and to purify you with a thorough purification."
And he (Sayyiduna Ali (may Allah be pleased with him)) was the first of the people to accept Islam after Sayyidah Khadijah (may Allah be pleased with her).
He narrated: Sayyiduna Ali (may Allah be pleased with him) put his life at risk: he put on the garment of the Prophet (peace and blessings be upon him) and then slept in his (peace and blessings be upon him) bed. He said that the polytheists (thinking him the Prophet (peace and blessings be upon him)) were shooting at the place where the Messenger of Allah (peace and blessings be upon him) (used to sleep).
Hadith Referenceالمعجم الأوسط / باب الألف / 2815
Hadith Takhrij«أخرجه الضياء المقدسي فى «الأحاديث المختارة» برقم: 35، 36، 37، 32، 33، 34، والحاكم فى «المستدرك» برقم: 4677، 4680، والنسائي فى «السنن الكبرى» برقم: 8355، 8373، 8374، 8548، والترمذي فى «جامعه» برقم: 3734، 3732، وأحمد فى «مسنده» برقم: 3119، 3120، 3612، والطيالسي فى «مسنده» برقم: 2875، 2876، والطحاوي فى «شرح مشكل الآثار» برقم: 3555، 3556، 3557، 3586، 4083، والطبراني فى «الكبير» برقم: 12594، 12593»