“what is terrible when you seek the truth is that you find it..”

149
Golden Sayings of Epictetus

as quoted by Paul Krassner in Lenny Bruce: Swear to tell the truth 1998 http://www.imdb.com/title/tt0175844/

Source: Thus Spoke Zarathustra

Source: Life, the Truth, and Being Free (2010), p. 73

H. Rosner, trans. (Bantam: 1971), p. 140
Siddhartha (1922)
Context: What could I say to you that would be of value, except that perhaps you seek too much, that as a result of your seeking you cannot find. … When someone is seeking, it happens quite easily that he only sees the thing that he is seeking; that he is unable to find anything, unable to absorb anything, because he is only thinking of the thing he is seeking, because he has a goal, because he is obsessed with his goal. Seeking means: to have a goal; but finding means: to be free, to be receptive, to have no goal. You, O worthy one, are perhaps indeed a seeker, for in striving towards your goal, you do not see many things that are under your nose.

Source: The Mysterious Affair at Styles

Variant: Don't seek happiness. If you seek it, you won't find it, because seeking is the antithesis of happiness. Happiness is ever elusive, but freedom from unhappiness is attainable now, by facing what is rather than making up stories about it. Unhappiness covers up your natural state of wellbeing and inner peace, the source of true happiness.
Source: A New Earth: Awakening to Your Life's Purpose

Source: The Man in the High Castle