"... Despite the fact that the book of Leviticus is not frequently quoted among those from the Pentateuch by Mark, Matthew and the Lukan writings, at least one clear allusion and five explicit quotations from Leviticus are to be found in the Synoptic Gospels and the Acts of the Apostles ... in the early second century CE, Rabbi Akiba “spoke of the same passage (Leviticus 19:18) as ‘the greatest general principle in the Torah’” (see Genesis Rabbah 24:7 and Sifra on Leviticus 19:18). Other pre-Christian Jewish sources which also include the summary of the law, are to be found in “Tobit 4:15 (compare Sirach 31:15), Letter of Aristeas 207-208 (with the positive also indicated), and the Jerusalem Targum of Leviticus 19:18.” Despite being rare, the positive form can also be found in pre-Christian Jewish literature (Letter of Aristeas 20; 2 Enoch 61:2; Pirkei Avot 2.10, 12) ... Some interesting intertextual connections regarding Leviticus 19:18 can also be found in both the Testament of Dan, as well as in the Testament of Issachar. But it is especially Leviticus 19:18 which displays a broad early Christian trajectory, covering the Pauline and Gospel traditions, the Western text, Acts 15:20 and 15:28, as well as the Didache (Didache 1:2), the early Church Fathers (Barnabas 19.5; Justin Martyr, Dialogue 93.2) and the Coptic Gospel of Thomas 6. It is no surprise that the New Testament writers frequently quote the so-called “golden rule”, or “rule of reciprocity” from Leviticus 19:18. They probably traced the origins of the “golden rule” back to a Logion in the Jesus-tradition which contained Jesus’ own summary of the law ..."

Steyn, Gert J. "The Text Form of the Leviticus Quotations in the Synoptic Gospels and the Acts of the Apostles" in Himbaza, Innocent (ed.) The Text of Leviticus: Proceedings of the Third International Colloquium of the Dominique Barthélemy Institute (pp. 205-242) Peeters, 2020