9 From this union of wills, indeed, which must be conspicuous in the clerical order, as we have already intimated, this advantage among others will follow: that the ministers of the sacraments will more efficaciously warn the faithful not to exceed the limits in preserving and vindicating the rights proper to each race, or by excessive partisanship not to do violence to justice and overlook the common advantages of the state. For we think that this, according to the circumstances of your various regions, should be the principal task of priests, to exhort the faithful, in season and out, to love one another; they should warn them constantly that he is not worthy of the name of Christian who does not fulfill in spirit and action the new command given by Christ that we love one another as He has loved us.
Source: Reputantibus (Vatican.va)