Roman Catechism 18.10

Chapter 18 — Part II: The Sacraments — The Holy Eucharist

Section 10. Whence it came to pass, that i. was called also the Sacrament of peace and love. We can understand then how unworthy they are of the name of Christian who cherish enmities, and how hatred, dissensions and discord should be entirely put away, as the most destructive bane of the faithful, especially since by the daily Sacrifice of our religion, we profess to preserve nothing with more anxious care, than peace and love.