The warning hadith (Arabic: یوْمُ الْاِنذار), also known as "invitation of the close families of Muhammad" (دعوة ذو العشیرة - Da‘wat dhul-‘Ashīrah) is a hadith that is recorded in all Muslim books through different chain of narration. Shi'a's use this hadith to prove Ali ibn Abi Talib's claim as the rightful successor to Muhammad.
Invitation of close families
For three years Muhammad invited people to Islam in secret. Then he started inviting people publicly. When, according to the Qur'an he was commanded to invite his closer relatives to come to Islam, and gathered the Banu Hashim in a ceremony and told them clearly that whoever would be the first to accept his invitation would become his successor and inheritor. Ali who was 10 or 11 years old at that time was the one to step forth and embrace Islam.
Ali, the one narrating the hadith, says Muhammad ordered him to cook food for forty people. After the food was presented and the people ate and drank, Muhammad stood up and said, "O sons of Abd al-Muttalib, by Allah, I do not know of any person among the Arabs who has come to his people with better than what I have brought to you and I have verily came to you with the best of this world and the hereafter, and Allah has ordered me to invite you to it. So who of you, will help me in this mission and to be my brother (akhī), my successor (waṣiyyī), and my caliph (khalīfatī) among you?"
Muhammad repeated this three times, no one present responded to him except the youngest of them—‘Ali b. Abī Tālib. He stood up and said, "I will be your helper, O Prophet of God" thrice.
Muhammad then put his hand on the back of Ali's neck and said, "Verily this is my brother, my successor, and my caliph amongst you; therefore, listen to him and obey." However a handful of the people then laughed and said to Abu Talib "Muhammed has ordered you to obey your son."