“Some knowledge is too heavy… you cannot bear it… your Father will carry it until you are able.”

Brother Zachariah, to Jace Herondale, pg. 233
The Mortal Instruments, City of Heavenly Fire (2014)

Source: The Mill on the Floss

Source: Haunted

As quoted in Homelessness in America : A Forced March to Nowhere (1982), p. 121
Context: You will find out that Charity is a heavy burden to carry, heavier than the kettle of soup and the full basket. But you will keep your gentleness and your smile. It is not enough to give soup and bread. This the rich can do. You are the servant of the poor, always smiling and good-humored. They are your masters, terribly sensitive and exacting master you will see and the uglier and the dirtier they will be, the more unjust and insulting, the more love you must give them. It is only for your love alone that the poor will forgive you the bread you give to them.

Source: The Wise Man's Fear

Though Buffet is reported to have expressed such ideas with such remarks many times in his lectures, he never claimed to originate the idea, and in the article "The Chains of Habit Are Too Light To Be Felt Until They Are Too Heavy To Be Broken" at the Quote Investigator http://quoteinvestigator.com/tag/warren-buffett/ it is shown that this sort of expression about chains goes back at least to similar ideas presented by Samuel Johnson in "The Vision of Theodore, The Hermit of Teneriffe, Found in His Cell" in The Gentleman’s Magazine, Vol. 18 (April 1748), p.160:
It was the peculiar artifice of Habit not to suffer her power to be felt at first. Those whom she led, she had the address of appearing only to attend, but was continually doubling her chains upon her companions; which were so slender in themselves, and so silently fastened, that while the attention was engaged by other objects, they were not easily perceived. Each link grew tighter as it had been longer worn, and when, by continual additions, they became so heavy as to be felt, they were very frequently too strong to be broken.
Such sentiments were later succinctly summarized by Maria Edgeworth in Moral Tales For Young People by Miss Edgeworth (1806), Vol 1, Second Edition, p. 86:
… the diminutive chains of habit, as somebody says, are scarcely ever heavy enough to be felt, till they are too strong to be broken.
Disputed

104
Golden Sayings of Epictetus

Pero el que no pudiere alcançar a tener la sabiduría en servidumbre, lógrela en familiaridad.
Maxim 15 (p. 9)
The Art of Worldly Wisdom (1647)