“Hell is truth known too late.”

Source: A Dictionary of Thoughts, 1891, p. 225.

No Country for Old Men (2005)

Source: The Tenth Circle

Source: The History of Love

Pt. I, line 343.
The Hind and the Panther (1687)

Source: As quoted in My Fellow Americans : The Most Important Speeches of America's Presidents (2003) by Michael Waldman, p. 137

Vorkosigan Saga, A Civil Campaign (1999)
Variant: The principal difference between heaven and hell is the company you keep there.

Act 4 http://books.google.com/books?id=YI8iwzZhl6AC&q=%22what+the+hell+was+it+I+wanted+to+buy+I+wonder+that+was+worth+well+no+matter+it's+a+late+day+for+regrets%22&pg=PT133#v=onepage
Long Day's Journey into Night (1955)

Vol. VI, p 5, "First Talk in Rajahmundry (20 November 1949) http://www.jkrishnamurti.com/krishnamurti-teachings/view-text.php?tid=335&chid=4655&w=%22You+cannot+find+truth+through+anybody+else%22, J.Krishnamurti Online, JKO Serial No. 491120
Posthumous publications, The Collected Works
Context: You cannot find truth through anybody else. How can you? Surely, truth is not something static; it has no fixed abode; it is not an end, a goal. On the contrary, it is living, dynamic, alert, alive. How can it be an end? If truth is a fixed point, it is no longer truth; it is then a mere opinion. Sir, truth is the unknown, and a mind that is seeking truth will never find it. For mind is made up of the known; it is the result of the past, the outcome of time — which you can observe for yourself. Mind is the instrument of the known; hence it cannot find the unknown; it can only move from the known to the known. When the mind seeks truth, the truth it has read about in books, that "truth" is self-projected, for then the mind is merely in pursuit of the known, a more satisfactory known than the previous one. When the mind seeks truth, it is seeking its own self-projection, not truth. After all, an ideal is self-projected; it is fictitious, unreal. What is real is what is, not the opposite. But a mind that is seeking reality, seeking God, is seeking the known. When you think of God, your God is the projection of your own thought, the result of social influences. You can think only of the known; you cannot think of the unknown, you cannot concentrate on truth. The moment you think of the unknown, it is merely the self-projected known. So, God or truth cannot be thought about. If you think about it, it is not truth. Truth cannot be sought; it comes to you. You can go after only what is known. When the mind is not tortured by the known, by the effects of the known, then only can truth reveal itself. Truth is in every leaf, every tear; it is to be known from moment to moment. No one can lead you to truth; and if anyone leads you, it can only be to the known.