Here is my translation and sources:
Power hungry Slytherin
loved those of great ambition.
In Slytherin you'll make
your real friends,
Those cunning folk use any
To achieve their ends.
SS/PS Ch 7, p.118 (softcover) The Sorting Hat from Harry's first year.
There is no good and evil, there is only power and
those too weak to seek it.
SS/PS Ch 17, p.291 Harry and Quirrelmort