The parable itself was pretty certainly dropped in this narrative by an editor because it kinda relates thematically. Remove it (vs8-15) and the narrative reads perfectly unbroken. But that is just another example of how the OT was stitched together from diverse material.
Another interesting point is the word for 'bush' used in Exodus occurs nowhere else and might have been a scribal error very early. 'סנה seneh' has long been assumed to mean a thorn bush but the similarity to 'סיני sinai' the name of the holy mountain (aka Horeb) reasonably suggests a scribal error.. Moses was told to remove his sandals as he was standing on holy ground at the base of Yahweh's holy mount Horeb/Sinai. That detail was always odd if the story actually featured a burning bush, just why was the ground holy?? But if Moses stood next to the burning mount Sinai and spoke to Yahweh it makes more sense in context.
If this is a correct reconstruction, the burning bush story was then meant to be a burning mountain story. But if the scribal error hadn't happened the writer of Judges couldn't have used it in the parable and the writer of Mark would not have had Jesus get a crown of thorns.
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