In this article I posit the presence of an early Jewish exegesis of Lev 19:17–18 preserved in the Tannaitic midrash known as Sifra, which is inverted and amplified in Did. 1:3–5, Q 6:27–35, Luke 6:27–35, and Matt 5:38–44. Identifying shared terminology and a sequence of themes in these passages, I argue that these commonalities testify to the existence of a shared exegetical tradition. By analyzing the later rabbinic material I delineate the contours of this Second Temple period interpretation and augment our understanding of the construction of these early Christian pericopae. In commenting on Lev 19:17, Sifra articulates three permissible modes of rebuke: cursing, hitting, and slapping. In its gloss on the subsequent verse, Sifra exemplifies the biblical injunction against vengeance and bearing a grudge through the case of lending and borrowing from one’s neighbor. The Didache, Matthew, and Luke invert the first interpretation by presenting Jesus as recommending a passive response to being cursed or slapped, and they amplify the second interpretation by commanding one to give and lend freely to all who ask. The similar juxtaposition of these two ideas and the shared terminology between Sifra and these New Testament period texts suggest a common source. By reading these early Christian sources in light of this later rabbinic work I advance our understanding of the formation of these well-known passages and illustrate the advantages of cautiously employing rabbinic material for reading earlier Christian works.