SHAFAQNA – In the year 10 AH, the Prophet of Islam (PBUH) sent Khalid bin Walid to Yemen in order to invite the big tribe of Hamdan and other tribes in Yemen to Islam. Khalid stayed with the tribes of Yemen for six months and even one person did not convert to Islam. Prophet Mohammad (PBUH) ordered Amiral Momeneen Ali (AS) to go to Yemen. Imam Ali (AS) reached Yemen and Khalid bin Walid returned. In one day of Imam Ali’s (AS) presence, all of the people of the big tribe of Hamdan, converted to Islam; and in less than a month, all the tribes of Yemen converted to Islam .
 Beharul Anwaar, Vol. 21, Page 363.