Various Rules of Conduct, Leviticus

You shall not hate any of your kindred in your heart. Reprove your neighbor openly so that you do not incur sin because of that person. Take no revenge and cherish no grudge against your own people. You shall love your neighbor as yourself. I am the LORD.

+ Book of Leviticus 19,17-18

http://www.usccb.org/bible/leviticus/19