“As I worked in the mountains, I will continue to work for the sacred fatherland with heart and soul in any kind of duty for which the fatherland employs me and any kind of task the fatherland expects from me.”

Out of My Life (London: Cassell, 1920), pp. 236-237
Retirement

Quoted in "Admiral Canaris - Chief of Intelligence" - Page 210 - by Ian Colvin - 2007

Last words, 10/16/46. Quoted in "The Mammoth Book of Eyewitness World War II" - Page 564 - by Jon E. Lewis - History - 2002

"Report on the Draft Amended Constitution", (December 18, 1959)
1950's

Testament (1969)
1960's

This, and variants of it, have been been widely circulated as a Quaker saying since at least 1869, and attributed to Grellet since at least 1893. W. Gurney Benham in Benham's Book of Quotations, Proverbs, and Household Words (1907) states that though sometimes attributed to others, "there seems to be some authority in favor of Stephen Grellet being the author, but the passage does not appear in any of his printed works." It appears to have been published as an anonymous proverb at least as early as 1859, when it appeared in Household Words : A Weekly Journal.
It has also often become attributed to the more famous Quaker William Penn, as well as others including Mahatma Gandhi and Ralph Waldo Emerson.
Variants:
I expect to pass through this world but once. If, therefore, there be any kindness I can show, or any good thing I can do any fellow human being let me do it now. Let me not defer or neglect it, for I will not pass this way again.
Writing of an unnamed Quaker, as quoted in Scott's Monthly Magazine Vol. VII, No. 6 (June 1869, p. 475, edited by William J. Scott
I expect to pass through this world but once. Any good thing, therefore, that I can do or any kindness I can show to any fellow human being let me do it now. Let me not defer nor neglect it, for I shall not pass this way again.
As quoted anonymously in Hour by Hour; or, The Christian's Daily Life (1885), compiled by E.A.L., p. 37, and as "the old Quaker's words" in The Unitarian Vol. VI (July 1891); this version was given the title "Do It Now" in Heart Throbs: In Prose and Verse (1905) by Joe Mitchell Chapple.
I shall pass through this world but once! Any good thing, therefore, that I can do or any kindness that I can show to any human being, let me do it now, in his name, and for his sake! Let me not defer or neglect it, for I shall not pass this way again.
Anonymous quotation on a card, as quoted in The Friend, Vol. 61 (1888) by The Society of Friends, p. 364
I shall pass through this world but once. Any good, therefore, that I can do or any kindness I can show to any human being, let me do it now. Let me not defer or neglect it, for I shall not pass this way again.
Anonymous quotation on a card, as quoted in A Memorial of a True Life : A Biography of Hugh McAllister Beaver (1898) by Robert Elliott Speer, p. 169
I expect to pass through this world but once. If, therefore, there be any kindness I can show, or any good thing I can do, to any fellow being let me do it now. Let me not defer nor neglect it, for I shall not pass this way again.
As quoted anonymously in The Lamp Vol. XXVI (February-July 1903)
Disputed

Speech held in Nevrokop during the Young Turk Revolution, July 1908 ; Republished by Ivan Diviziev. Istoricheski Pregled, 1964, Book 4

This quote is often attributed to William Penn, but there are no records of it before the 19th century, and its actual source seems to have most likely been another prominent Quaker, Stephen Grellet.
Misattributed

De Abaitua interview (1998)
Context: Take disintegration far enough and you get a new form of integration. I tend to see all this in neural terms. It doesn’t matter how big your brain is, or how many cells or neurons in it, what matters is the synaptic fusions, the connections that determine how intelligent you are. As with the individual, so with the macrocosm. That’s how the kind of society I live in works, me and my friends and my contacts, we don’t work in any hierarchical sense. No one wants a boss, to be a boss, to work under a boss. The people you like working with are the people you respect as individuals.