What internal evidence supports the historicity of Abraham?

Is there any internal or small external evidence of Abraham's existence? I have heard a claim from skeptics that Abraham is just flat out invented figure who never existed and even COULDN'T have existed. > Not only has archaeology not proven a single event of the patriarchal traditions to be historical, it has not shown any of the traditions to be likely. - Thomas L. Thompson, [*The Historicity of the Patriarchal Narratives: The Quest for the Historical Abraham*](https://en.wikipedia.org/wiki/The_Historicity_of_the_Patriarchal_Narratives) (BZAW 133, De Gruyter, Berlin and New York, 1974), page 328 Is this valid? *Note that I am not asking for extra-biblical mentions of Abraham.* I am realistic, he was unimportant nomad in illiterate world. However, I am asking, is there any evidence for events and places and customs described in Genesis? Is there any internal evidence in the text itself like criteria of embarrassment or something that must be historical? I have always seen Abraham's life as too simple and non-embellished and non-fantastical for him to be made up. Beyond that, I never saw any other evidence for his historicity.