A king of ‘Uman to whom Muhammad sent a despatch inviting him to Islam, which event led eventually to the conversion of that province.
“On his return from the seige of Tayif, towards the close of the eight year of the Hegira, Mahomet sent Amru with a despatch to Jeyfar, King of Oman, summoning him and his brother to make profession of the true faith. At first they gave answer ‘that they would be the weakest among the Arabs, if they made another man possessor of their property.’ But as Amru was about to depart, they repented, and , calling him back, embraced Islam. The people followed their example, and without demur paid their tithes to Amru, who continued till the Prophet’s death to be his representative in Oman.” (Muir’s Life of Mahomet, new ed. p. 471.)
Based on Hughes, Dictionary of Islam