Freud, in Future of an Illusion, Civilization and its Discontents,
quotes a German, obviously, maybe Goethe or Schiller or Brecht. I dont
have that book with me right now.

This is about it:

I would like a house with a garden and three trees. I would like my
enemies to hang from these trees. I do sincerely forgive them but I
would like to see them hang.

Something like that.

I would like to know whom Freud quotes. Name of the author and the
work. Maybe the exact quote too, but not required.

"Mine is a most peaceable disposition. My wishes are: a humble cottage
with a thatched roof,
but a good bed, good food, the freshest milk and butter, flowers before my window, 
and a few fine trees before my door; and if God wants to make my
happiness complete,
he will grant me the joy of seeing some six or seven of my enemies
hanging from those trees.
Before their death I shall, moved in my heart, forgive them all the
wrong they did me in their lifetime.
One must, it is true, forgive one's enemies - but not before they have
been hanged." - Heine

Here's the original, by the way:

Ich habe die friedlichste Gesinnung. 
Meine Wünsche sind: eine bescheidene Hütte, ein Strohdach, aber ein gutes Bett, 
gutes Essen, Milch und Butter, sehr frisch, vor dem Fenster Blumen, vor der Tür 
einige schöne Bäume, und wenn der liebe Gott mich ganz glücklich machen will, 
lässt er mich die Freude erleben, dass an diesen Bäumen etwa sechs bis sieben 
meiner Feinde aufgehängt werden. 

Mit gerührtem Herzen werde ich ihnen vor ihrem Tode alle Unbill verzeihen, - 
die sie mir im Leben zugefügt - ja, man muß seinen Feinden verzeihen, aber 
nicht früher, als bis sie gehenkt werden.

(Heinrich Heine, Gedanken und Einfälle)

Ui, that was very quick, thought it would be more difficult to get by.
Thank you very much. I think I can't pay you via Google, though you
deserve it. I better cancel then. Thanks.