In Shakespeare's Hamlet, Claudius (Hamlet's Uncle) becomes the new King of Denmark after the death of Hamlet's father and Claudius's marriage to Hamlet's mother.

Act 1, scene 2 begins with Claudius addressing the court:

Though yet of Hamlet our dear brother's death
The memory be green, and that it us befitted
To bear our hearts in grief, and our whole kingdom
To be contracted in one brow of woe,
Yet so far hath discretion fought with nature
That we with wisest sorrow think on him
Together with remembrance of ourselves.
Therefore our sometime sister, now our queen,
Th' imperial jointress to this warlike state,
Have we, . . .
Taken to wife

While acknowledging that he is saddened by his brother's death, Claudius explains that it is important to move on quickly from the sorrow, and so he has married his brother's wife. This is a dishonor to Prince Hamlet, because he has become Hamlet's stepfather before Hamlet has had time to properly grieve for his father.

Later in the same scene, he says to Hamlet, "How is it that the clouds still hang on you?" In this quote, Claudius is basically asking, "Why are you still sad?" This is not something one should say to a grieving son.

Claudius goes on to say:

'Tis sweet and commendable in your nature, Hamlet,
To give these mourning duties to your father;
But you must know, your father lost a father;
That father lost, lost his, and the survivor bound
In filial obligation for some term
To do obsequious sorrow. But to persever
In obstinate condolement is a course
Of impious stubbornness. 'Tis unmanly grief;
It shows a will most incorrect to heaven,
A heart unfortified, a mind impatient,
An understanding simple and unschool'd;
. . . We pray you throw to earth
This unprevailing woe, and think of us
As of a father

In this passage, Claudius tells Hamlet that he should move on: he calls Hamlet's grief "unmanly." By pointing out that "your father lost a father" and so on, Claudius is trying to say that death is a natural progression and therefore suggests that Hamlet should not be saddened by death. Then Claudius tells Hamlet to think of him as a father.

Claudius is therefore disrespectful to his nephew (and by extension, the memory of his brother) by not letting him grieve.