Heraclius

Heraclius was the Roman (Byzantine) emperor from 610 to 641 CE. After Persia overran much of his empire, he recovered almost all of it, as Surah al-Rum had foretold, and defeated Khosrow II by 628 CE. An educated scholar of Christianity, he received the Prophet ﷺ's letter inviting him to Islam, questioned Abu Sufyan about the Prophet ﷺ, and privately recognized him as a true prophet, but he chose to keep his throne and remained a Christian. He never personally led an army against the Muslims, and he lived to see Jerusalem conquered by them.