Campaign in Yemen. On being ousted from power, Feroz who remained true to Islam sought help from Abu Bakr. Qais apostatized from Islam, and won the cooperation of all those who had previously supported Aswad'Ansi. Some tribes in Yemen, however, remained firm in their faith in Islam, and they rallied round Feroz. With the aid of these tribes, Feroz sallied down from the hills and advanced against Sana'a the capital of Yemen There was a confrontation in the plain outside Sana'a. In this confrontation, the forces of Qais were defeated, and he found safety in flight. Feroz once again became the ruler of Yemen. The restoration of Feroz did not bring peace to Yemen. Qais though defeated continued to be a source of trouble. He approached the Arab tribes and tried to win them to his cause in opposition to Feroz. Qais succeeded in winning Umr bin Maadi Kurb to his side. Umr was a poet and a firebrand fighter and his alliance with Qais made the position of Feroz difficult.

Feroz appealed to Abu Bakr for help. Abu Bakr ordered a two-pronged advance on Yemen. Muhajir b Umayya was directed to march from Makkah to Yemen. 'Ikramah bin Abu Jahal was directed to march from Mahrah to Yemen. 'Ikramah entered Yemen and camped at Abyan. Muhajir with his force advanced from Makkah and Taif. At the border of Yemen a tribe allied with Qais intercepted the advance of the force of Muhajir. The Muslims charged with great fury, and in the battle that ensued practically the whole of the tribe was exterminated. This victory of the Muslims unnerved the apostates. Instead of making common cause to give another battle to the Muslims, Qais and Umr fell out with each other. One day Umr surprised Qais and after taking him captive presented him before Muhajir, Umr had hoped that thereby he would win the favor of Muhajir. Muhajir, however, arrested Umr as well for his past misconduct. With the elimination of the two leaders, the apostate tribes had no will to fight. They laid down arms. and those who accepted Islam were granted amnesty, the rest were killed. That brought peace to Yemen. Qais and Umr were both sent in chains to Madina and there they were presented before Abu Bakr. At Madina, both Qais and Umr repented and were re-admitted to the fold of Islam.