Leviticus 19:18
16 You must not go about as a slanderer among your people. You must not stand idly by when your neighbor’s life is at stake. I am the Lord. 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. 20 “‘When a man goes to bed with a woman for intercourse, although she is a slave woman designated for another man and she has not yet been ransomed, or freedom has not been granted to her, there will be an obligation to pay compensation. They must not be put to death, because she was not free.
James 2:8
6 But you have dishonored the poor! Are not the rich oppressing you and dragging you into the courts? 7 Do they not blaspheme the good name of the one you belong to? 8 But if you fulfill the royal law as expressed in this scripture, “You shall love your neighbor as yourself,” you are doing well. 9 But if you show prejudice, you are committing sin and are convicted by the law as violators. 10 For the one who obeys the whole law but fails in one point has become guilty of all of it.
Notes and References
"... The teacher (or person) who avoids stumbling in speaking is 'perfect.' By now the careful reader of James is familiar with this term. James has spoken of believers being 'mature and complete' in 1:4, of God's gifts as 'perfect' in 1:17, and more importantly of the 'law of liberty' being the 'perfect law' in 1:25. The law of liberty in 1:25 is a synonym for the 'royal law,' the second half of the Jesus Creed (e.g., Leveticus 19:18) in 2:8. Thus, when James speaks of a 'perfect' teacher in 3:2, his concern is more focused than on just Torah observance. This person is a fully developed follower of Jesus' own teachings of the Torah as the Torah of loving God and loving others. The perfect teacher is one whose love shapes how he or she teaches and speaks of others ..."
McKnight, Scot The Letter of James (p. 275) William B. Eerdmans Publishing Company, 2011