Letters Of Prophet (sws) To Roman And Persian Empires & Their Historical Status
This is an established fact of history. This led to the battle of Muta and then Tabuk and many other events. This is not just a single incident. If one denies it, one has to deny the whole chain of events which resulted in conflict with Byzantine and Persia and that is not possible.
Please also refer to the video below from 29:52 to 31:57 https://youtu.be/GhbLv0QPwqA?si=5FA4XWxXTnmESeDC&t=1792