“Caesar exclaimed: "Let us accept this as a sign from the Gods, and follow where they beckon, in vengeance on our double-dealing enemies. The die is cast."”

Christmas in India, Stanza 5.
Departmental Ditties and other Verses (1886)

This passage contains some phrases King later used in "Where Do We Go From Here?" (1967) which has a section below.
1950s, Loving Your Enemies (Christmas 1957)
Context: Let us move now from the practical how to the theoretical why: Why should we love our enemies? The first reason is fairly obvious. Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that. Hate multiplies hate, violence multiplies violence, and toughness multiplies toughness in a descending spiral of destruction. So when Jesus says "love your enemies," he is setting forth a profound and ultimately inescapable admonition. Have we not come to such an impasse in the modern world that we must love our enemies-or else? The chain reaction of evil-Hate begetting hate, wars producing more wars-must be broken, or we shall be plunged into the dark abyss of annihilation.

Yo soy un hombre sincero
De donde crece la palma
Y antes de morirme quiero
Echar mis versos del alma.
I (Yo soy un hombre sincero) as translated by Esther Allen in José Martí : Selected Writings (2002), p. 273, ISBN 0142437042
Variant translations:
A sincere man am I
From the land where palm trees grow,
And I want before I die
My soul's verses to bestow.
"A Sincere Man Am I" http://oldpoetry.com/opoem/46409-Jose-Marti-A-Sincere-Man-Am-I---Verse-I-, as translated by Manuel A. Tellechea, in Versos Sencillos: Simple Verses (1997) ISBN 1558852042
I am a sincere man
from where the palm tree grows,
and before I die I wish
to pour forth the verses from my soul.
Simple Verses (1891)

Source: Dialogues of the Soul and Mortal Self in Time (1975), p. 76

Rajagopalachari (12 February 1949), quoted in [Rajmohan Gandhi, Rajaji: A Life, http://books.google.com/books?id=JjPHeRd7_UYC&pg=PA475, 1997, Penguin Books India, 978-0-14-026967-3, 286]
Spoken by C.R when Mahatma Gandhi (Bapu) was assassinated.

1920s, Toleration and Liberalism (1925)
Context: It is for these reasons that it seems clear that the results of the war will be lost and we shall only be entering a period of preparation for another conflict unless we can demobilize the racial antagonisms, fears, hatreds, and suspicions, and create an attitude of toleration in the public mind of the peoples of the earth. If our country is to have any position of leadership, I trust it may be in that direction, and I believe that the place where it should begin is at home. Let us cast off our hatreds. Let us candidly accept our treaties and our natural obligations of peace. We know and everyone knows that these old systems, antagonisms, and reliance on force have failed. If the world has made any progress, it has been the result of the development of other ideals. If we are to maintain and perfect our own civilization, if we are to be of any benefit to the rest of mankind, we must turn aside from the thoughts of destruction and cultivate the thoughts of construction. We can not place our main reliance upon material forces. We must reaffirm and reinforce our ancient faith in truth and justice, in charitableness and tolerance. We must make our supreme commitment to the everlasting spiritual forces of life. We must mobilize the conscience of mankind.

Reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 257.