That even our enemies must be loved
In the Gospel according to Luke: “If you love those who love you, what reward do you have? For even sinners love those who love them.” Also according to Matthew: “Love your enemies, and pray for those who persecute you, that you may be the children of your Father who is in heaven, who makes His sun to rise upon the good and the evil, and gives rain upon the righteous and the unrighteous.”
Source: The Treatises of Cyprian (New Advent)