In Macbeth, what arguments does Macbeth raise for not killing Duncan in Act I scene vii?

I take it you are referring to the soliloquy that Macbeth
gives in Act I scene 7. This is a very important speech that Macbeth gives because in it
he reveals something of his doubt and inner anguish about the act as he begins to have
second thoughts. Initially, Macbeth starts off by talking about the best way to do it,
saying that if it were done quickly, it might limit the possibilities for reprisals.
Macbeth says that, for the glory that he could gain, he would "jump the life to come,"
as in risk the judgement that he might receive by committing the crime of
regicide.

However, Macbeth still fears vengeance. He says
that by killing Duncan he would teach "Bloody instructions" that "return / To plage
th'inventor." Killing Duncan might find Macbeth himself killed out of revenge, which is
of course precisely what happens. Then Macbeth goes on to talk about reasons why he
shouldn't kill Duncan. Firstly he is Duncan's subject and secondly his host - Macbeth
would break trust in a massive fashion were he to kill Duncan. He also says that Duncan
has been such a pious and "meek" king that to kill him would surely bring eternal
damnation. Lastly, he uses an unforgettable metaphor to describe his
ambition:

I
have no spur

To prick the sides of my intent, but
only

Vaulting ambition, which o'erleaps
itself

And falls on th'other
-

He says the only quality he
can use to convince himself to kill Duncan is his ambition, which can be likened to
someone who is to eager to ride and therefore jumps so hard and so high when mounting
the horse they fall completely on the other side.

Thus
Macbeth is concerned about a whole series of possible outcomes to committing murder,
fearing both judgement in this world and in the world to come. Crucially, however, Lady
Macbeth manages to persuade him in the rest of this scene in what must be one of the
best examples of manipulation in literature.