References to Jacob and Esau proliferate in Jewish and Christian late antique and medieval texts.Recent scholarship has focused on this material to present Christian–Jewish relations through the prism of sibling rivalry. This chapter focuses on the Glossa ordinaria and the commentary of Rashi on Genesis chapters 25 and 27 to explore how exegetes used the story of the struggle between Jacob and Esau to express their own collective religious identity and how they employed the shared material to characterise the religious other. It examines how the narrative was used by commentators to pass judgement on members of their own religious communities and how these internal evaluations interacted with external assessments. The purpose of the chapter is to gain a deeper understanding of how medieval Jews and Christians internalised the claims made by their respective religious traditions as well as to explore whether the image of fraternal rivalry adequately encapsulates the ambiguous and paradoxical relationship between medieval Christianity and Judaism.