'A Poison Tree'
I was angry with my friend:
I told my wrath, my wrath did end.
I was angry with my foe:
I told it not, my wrath did grow.
And I water'd it in fears,
Night and morning with my tears;
And I sunned it with smiles,
And with soft deceitful wiles.
And it grew both day and night,
Till it bore an apple bright;
And my foe beheld it shine,
And he knew that it was mine,
And into my garden stole
When the night had veil'd the pole:
In the morning glad I see
My foe outstretch'd beneath the tree.
From Songs of Experience
with thanks to Peter Kalnin for pointing out the typo.
picture credit: http://www.polbox.com/m/maurycyk/drzewo.html