Hazrat Khalid was an expert of military law. Huzur ﷺ best wanted to take his services in issuing orders and spreading Islam. If such a courageous person who has suffered many tortures and is ready to sacrifice his own life, acquires efficiency in this field, he would achieve the highest targets. For this, after the incidence of Bani Jazima, in Hijri 8, he was allotted the work of spreading Islam. He was sent to Yemen for the spread of Islam. But, at the same time, he was warned very strongly that none of the strict steps should be taken.
He tried for six months, but it was in vain and did not yield any result. In this connection, Allama Shibli writes, “Now, when Huzur ﷺ sent Hazrat Ali AlaihisSalam for the spread of Islam, and when he propagated Islam before them, very soon, country after country accepted Islam.” (Sirat-un-Nabi , Vol-II)
This incidence is about one of the famous places of Yemen where the habitants of Hamdan dwell. This was the biggest and most populated region with very impressive people. The whole group became Muslim due to Hazrat Ali AlaihisSalam very effective efforts for the spread of Islam. When Hazrat Ali AlaihisSalam sent this information to the house of Rasulﷺ, Huzur ﷺ offered Sajda, and after raising the head, said twice, “Let Hamdan be protected.”Due to a great impact of Hazrat Ali AlaihisSalam on the residents of Yemen, they mixed whole-heartedly with him. Based on this Hazrat Ibn-e-Abbas suggested Hazrat Imam-e-Husain (when he was on his way to Kufa) that “You, please go to Yemen. There are many believers of your holy father.”
And Huzur ﷺ was also very much pleased with the people of Yemen, and he considered their faith to be of great value. In the Sahihain’s Hadith, it is said that “the Yemeni’s faith and wisdom are real faith and wisdom, in the right sense of the terms.” (Mishkar)
Huzur ﷺ appointed Hazrat Ali AlaihisSalam as a judge of Yemen. For this, he stayed there for some time and undertook the activity of spreading Islam. As a result of this, Islam was spread all over Yemen. When Huzur ﷺ left for Hajj in Hijri 10, Hazrat Ali AlaihisSalam in Yemen, and from there only he left for Hajj.