Paul opens his First Epistle to the Corinthians with the exhortation “Now I appeal to you, brothers [and sisters], … that there be no divisions among you, but that you be united in the same mind and the same purpose” (1:10). This plea is strikingly similar to a passage in Sifre Deuteronomy 96, where the words lo titgodedu are interpreted as “Do not be made into gatherings/factions [ʾagudot]; rather, be all of you one gathering [ʾagudah].” Analyzing these sources in depth, this article argues that Paul was familiar with this early rabbinic midrash in an oral form. It also explores the possibility that Paul used another early rabbinic tradition on unity, which is found in the Mekhilta de-miluʾim section of the Sifra. If Paul indeed knew certain rabbinic oral traditions, then he was an independent interpreter of Scripture, who read Scripture in the original Hebrew. Further, even if Paul's audience consisted primarily of gentiles, the legal norms he sought to institute among them were based on Jewish traditions. Finally, Paul follows his exhortation against schismata with the names of specific groups in Corinth, which demonstrates that he understood the tannaitic tradition as a normative principle, meant to be applied to specific disagreements. If so, other first-century Jews also likely understood lo titgodedu as a concrete halakhic prohibition.