40 And to render such friendship between God and mankind more intimate, this same Divine and universal Mediator of salvation and of peace, in the sacred silence of the Supper Room, before He consummated the Supreme Sacrifice, let fall from His divine Lips the words which reverberate mightily down the centuries, inspiring heroic charity in a world devoidof love and torn by hate: "This is my commandment that you love one another, as I have loved you" ( Saint John xv. 12).
Source: Summi Pontificatus (Vatican.va)