Irenæus on the Golden Rule (and more)

"the working of liberty is greater and more glorious than that obedience which is rendered in [a state of] slavery. 3. And for this reason did the Lord, instead of that [commandment], “Thou shalt not commit adultery,” forbid even concupiscence; and instead of that which runs thus, “Thou shalt not kill,” He prohibited anger; and instead of the law enjoining the giving of tithes, [He told us] to share 3953 all our possessions with the poor; and not to love our neighbours only, but even our enemies; and not merely to be liberal givers and bestowers, but even that we should present a gratuitous gift to those who take away our goods. For “to him that taketh away thy coat,” He says, “give to him thy cloak also; and from him that taketh away thy goods, ask them not again; and as ye would that men should do unto you, do ye unto them:” 3954 so that we may not grieve as those who are unwilling to be defrauded, but may rejoice as those who have given willingly, and as rather conferring a favour upon our neighbours than yielding to necessity. “And if any one,” He says, “shall compel thee [to go] a mile, go with him twain;” 3955 so that thou mayest not follow him as a slave, but may as a free man go before him, showing thyself in all things kindly disposed and useful to thy neighbour, not regarding their evil intentions, but performing thy kind offices, assimilating thyself to the Father, “who maketh His sun to rise upon the evil and the good, and sendeth rain upon the just and unjust.” 3956 Now all these [precepts], as I have already observed, were not [the injunctions] of one doing away with the law, but of one fulfilling, extending, and widening it among us; just as if one should say, that the more extensive operation of liberty implies that a more complete subjection and affection towards our Liberator had been implanted within us. For He did not set us free for this purpose, that we should depart from Him (no one, indeed, while placed out of reach of the Lord’s benefits, has power to procure for himself the means of salvation), but that the more we receive His grace, the more we should love Him. Now the more we have loved Him, the more glory shall we receive from Him, when we are continually in the presence of the Father." (Against Heresies, 4.13.3-4)