Umayr bin Sa'd narrates: Sayyiduna Ali (may Allah be pleased with him) gathered the people at al-Rahbah (an open square), and I was present. He said: "I ask, by Allah, the man who heard the Prophet (peace and blessings be upon him) say: 'Whoever I am the mawla of, Ali is also his mawla.'" (The narrator says:) Eighteen men stood up and bore witness that they had heard the Prophet (peace and blessings be upon him) say that.
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14634
Hadith Gradingمحدثین:إسنادہ حسن۔
Hadith Takhrij«اخرجه الطبراني فى المعجم الاوسط (2131)»