“ACCORDING TO the numerous deductions and conclusions made by me during experimental elucidations concerning the productivity of the perception by contemporary people of new impressions from what is heard and read, and also according to the thought of one of the sayings of popular wisdom I have just remembered, handed down to our days from very ancient times, which declares: “Any prayer may be heard by the Higher Powers and a corresponding answer obtained only if it is uttered thrice:
:Firstly—for the welfare or the peace of the souls of one’s parents.
:Secondly—for the welfare of one’s neighbor.
:And only thirdly—for oneself personally.”

preface of his The World as Will and Representation., quoted in Londhe, S. (2008). A tribute to Hinduism: Thoughts and wisdom spanning continents and time about India and her culture. New Delhi: Pragun Publication.
The World as Will and Representation (1819; 1844; 1859)

"Friendly Advice [Written impromptu by the author on delivering this book, already prepared for publication, to the printer" (1949)
All and Everything: Beelzebub's Tales to His Grandson (1950)

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 462.

Pearls of Wisdom

"Blue Moon" (1934)

The History of the Quakers (1762)
Context: You have already heard that the Quakers date their epoch from Christ, who, according to them, was the first Quaker. Religion, say they, was corrupted almost immediately after His death, and remained in that state of corruption about sixteen hundred years. But there were always a few of the faithful concealed in the world, who carefully preserved the sacred fire, which was extinguished in all but themselves; till at length this light shone out in England in 1642.
It was at the time when Great Britain was distracted by intestine wars, which three or four sects had raised in the name of God, that one George Fox, a native of Leicestershire, and son of a silk-weaver, took it into his head to preach the Word, and, as he pretended, with all the requisites of a true apostle; that is, without being able either to read or write. He was a young man, about twenty-five years of age, of irreproachable manners, and religiously mad. He was clad in leather from head to foot, and travelled from one village to another, exclaiming against the war and the clergy.

[9, 88, 219]
Sunni Hadith

Canto IV, lines 133–135 (tr. C. E. Norton).
The Divine Comedy (c. 1308–1321), Purgatorio

Ausdehnungslehre (1844)