Sa'd ibn Ubadah
Mus‘ab ibn Umayr was appointed the first ambassador of Islam and was sent to Yathrib (Medina) to prepare the city for the forthcoming Hijra after the first pledge with the ansar. A man of Medina named Asad ibn Zurarah assisted him. After they had preached Islam, many residents of Medina were converted, including Sa'd ibn Mu'adh, Usayd ibn Hudayr and Sa'd ibn Ubadah. The Medinan converts were known as "Ansars" ("helpers").