When the Lord says, “Thou shalt love the Lord thy God, from all thy heart and from all thy mind: and thou shalt love thy neighbour as thyself” (Matt. 22:37, 39), let the faithful soul put on the unfading love of its Author and Ruler, and subject itself also entirely to His will in Whose works and judgments true justice and tender-hearted compassion never fail.
For although a man be wearied out with labours and many misfortunes, there is good reason for him to endure all in the knowledge that adversity will either prove him good or make him better.
But this godly love cannot be perfect unless a man love his neighbour also. Under which name must be included not only those who are connected with us by friendship or neighbourhood, but absolutely all men, with whom we have a common nature, whether they be foes or allies, slaves or free.
For the One Maker fashioned us, the One Creator breathed life into us; we all enjoy the same sky and air, the same days and nights, and, though some be good, others bad, some righteous, others unrighteous, yet God is bountiful to all, kind to all.
[…] But the wide extent of Christian grace has given us yet greater reasons for loving our neighbour, which, reaching to all parts of the whole world, looks down on no one, and teaches that no one is to be neglected.
And full rightly does He command us to love our enemies, and to pray to Him for our persecutors, who, daily grafting shoots of the wild olive from among all nations upon the holy branches of His own olive, makes men reconciled instead of enemies, adopted sons instead of strangers, just instead of ungodly, “that every knee may bow of things in heaven, of things on earth, and of things under the earth, and every tongue confess that the Lord Jesus Christ is in the glory of God the Father” (Phil. 2:10-11).
[…] There are three things which most belong to religious actions, namely prayer, fasting, and almsgiving, in the exercising of which while every time is accepted, yet that ought to be more zealously observed, which we have received as hallowed by tradition from the apostles: even as this tenth month brings round again to us the opportunity when according to the ancient practice we may give more diligent heed to those three things of which I have spoken.
This threefold round of duty, dearly beloved, brings all other virtues into action: it attains to God’s image and likeness and unites us inseparably with the Holy Spirit. Because in prayer faith remains stedfast, in fastings life remains innocent, in almsgiving the mind remains kind.
Leo the Great (c.400-461): Sermon 12:2&4.