A letter was sent from Muhammad to the emperor of Byzantium, Heraclius, through the Muslim envoy Dihyah Kalbi, although Shahid suggests that Heraclius may never have received it.[1] He also advances that more positive sub-narratives surrounding the letter contain little credence. According to El-Cheikh, Arab historians and chroniclers generally did not doubt the authenticity of Heraclius' letter due to the documentation of such letters in the majority of both early and later sources.[45] Furthermore, she notes that the formulation and the wordings of different sources are very close and the differences are ones of detail: They concern the date on which the letter was sent and its exact phrasing.[45] Muhammad Hamidullah, an Islamic research scholar, argues for the authenticity of the letter sent to Heraclius, and in a later work reproduces what is claimed to be the original letter.[45][46] The account as transmitted by Muslim historians reads as follows:[45]