Something is rotten in the state of Denmark

What’s the origin of the phrase ‘Something is rotten in the state of Denmark’?

The meaning and origin of the phrase ‘Something is rotten in the state of Denmark’ From Shakespeare’s Hamlet, Act I, Scene 4, 1602:

HAMLET
My fate cries out,
And makes each petty artery in this body
As hardy as the Nemean lion’s nerve.
Still am I call’d. Unhand me, gentlemen.
By heaven, I’ll make a ghost of him that lets me!
I say, away! Go on; I’ll follow thee.
Exit Ghost and HAMLET

HORATIO
He waxes desperate with imagination.
MARCELLUS
Let’s follow; ‘tis not fit thus to obey him.
HORATIO
Have after. To what issue will this come?
MARCELLUS
Something is rotten in the state of Denmark.
HORATIO
Heaven will direct it.
MARCELLUS
Nay, let’s follow him.