Leviticus 19:18
17 You must not hate your brother in your heart. You must surely reprove your fellow citizen so that you do not incur sin on account of him. 18 You must not take vengeance or bear a grudge against any of your people, but you must love your neighbor as yourself. I am the Lord. 19 You must keep my statutes. You must not allow two different kinds of your animals to breed together, you must not sow your field with two different kinds of seed, and you must not wear a garment made of two different kinds of material.
Sirach 28:2
Ben Sira, Ecclesiasticus2 Forgive your neighbor the wrong he has done, and then your sins will be pardoned when you pray. 3 Does anyone harbor anger against another, and expect healing from the Lord? 4 If one has no mercy toward another like himself, can he then seek pardon for his own sins? 5 If a mere mortal harbors wrath, who will make an atoning sacrifice for his sins?
Notes and References
"... By the New Testament period there were already indications that the comparative pronoun should be understood to refer to the subject, i.e. “You shall love your neighbor who is like you,” rather than the predicate, “You shall love your neighbor as you love yourself.” ... This interpretation recognized universal human frailty that necessitates divine mercy for all and precludes harsh judgment, a man against his neighbor: “Judge not, and you will not be judged; condemn not, and you will not be condemned; forgive, and you will be forgiven” (Luke 6:37). This intricate triangulation of God, the individual, and his neighbor is closely identified with the teaching of Jesus, but in fact it advances upon the conclusions of the preceding generations. Already in Ben Sira (175 BCE) we hear a similar triangulation with an allusion to Leviticus 19:18b. Likewise, the combination of Deuteronomy 6:5 and Leviticus 19:18 is not original with the New Testament. It is heard in Jubilees 20:2, 7; 36:4-8; Testament of Issachar 5:2; Testament of Dan 5:3; Philo, Special Laws 2:63; Sibyllene Oracles 8:480-82 ..."
Notley, R. Steven and Jeffrey P. Garcia "The Hebrew Scriptures in the Third Gospel" in Evans, Craig A. (ed.) Searching the Scriptures: Studies in Context and Intertextuality (pp. 128-147) Bloomsbury T&T Clark, 2015