And where would she have gotten this idea?
Khadijah had two cousins or uncles who had converted (from polytheism) to Christianity. One went to Constantnople and became what we call Eastern Orthodox. The other, Waraqah bin Naufal, become what we (somewhat confusingly) call Oriental Orthodox, or Nestorian/Monophysite: Another branch of early Christianity connected neither to Rome nor to Constantinople.
I'm not saying Khadijah was some kind of Christian. I'm supposing she knew a bit of Christian teaching from her Orthodox or Bestorian kin and her business dealings with Christians who ware commercial travelers.
It was this vaguelyChristian theological framework which gave her the confidence tosay, "Shaitan? Oh, no, it must have been Jibreel. You know, according to the ancient writings, the entity who visits you from God is always Jibreel."
Excellent information. Thanks. It is interesting that the story would follow the Bible, in that Kadija(Eve) misled Mohammed(Adam) due perhaps to her misunderstanding of the entity.