Who does Claudius say O this is the poison of a deep grief it springs all from her fathers death to?

In Shakespeare's Hamlet, Claudius refers to the deep grief stemming from Ophelia's father's death, which is Polonius. He acknowledges that her sorrow is profound and linked to the tragic events surrounding her family, particularly the impact of her father's murder by Hamlet. Claudius uses this observation to manipulate the situation, recognizing Ophelia's vulnerability as he navigates the political and personal turmoil in the court.