This is how our Saviour taught us diligently to manifest love: first he perfected it in himself, and then he taught those who heard him.
He reconciled our enmity with his Father because he loved us, and he yielded up his innocence in the place of the debtors, and the Good in place of the evil ones was put to shame, and the rich in our behalf was made poor, and the Living died in behalf of the dead, and by his death made alive our death. And the Son of the Lord of all took for our sake the form of a servant, and he to whom all things were subject subjected himself that he might release us from the subjection of sin. And by his great love he gave a blessing to the poor in spirit, and he promised the peace makers they should be called his brothers and sons of God; and he promised the humble that they should inherit the land of life; and he promised the mourners that by their supplications they would be comforted; and he promised to the hungry fullness in his Kingdom; and to those who weep that they should rejoice in his promise; and he promised to the merciful that they should be shown mercy; and to these who are pure in heart he said that they should see God; and again he promised to those who are persecuted on account of righteousness that they should go into the Kingdom of heaven; and to those who are persecuted on account of his name he promised a blessing and rest in his Kingdom. All these things our Saviour did for us because of his great love.
And we also, beloved, should share the love of Christ, while we love one another and fulfill those two commandments, on which hang all the Law and the prophets.
Aphrahat, Demonstration 2, 19