"There are two ways, one of life and one of death, but a great difference between the two ways. The way of life, then, is this: First, you shall love God who made you; second, love your neighbor as yourself, and do not do to another what you would not want done to you. And of these sayings the teaching is this: Bless those who curse you, and pray for your enemies, and fast for those who persecute you. For what reward is there for loving those who love you? Do not the Gentiles do the same? But love those who hate you, and you shall not have an enemy. Abstain from fleshly and worldly lusts. If someone strikes your right cheek, turn to him the other also, and you shall be perfect. If someone impresses you for one mile, go with him two. If someone takes your cloak, give him also your coat. If someone takes from you what is yours, ask it not back, for indeed you are not able. Give to every one who asks you, and ask it not back; for the Father wills that to all should be given of our own blessings (free gifts). Happy is he who gives according to the commandment, for he is guiltless... "
(The Didache - The Teaching of the Twelve Apostles, ch. 1, Roberts-Donaldson English Translation, c. 50-120 AD)