_Macb._ I think not of them:
Yet, when we can entreat an hour to serve,
We would spend it in some words upon that business,
If you would grant the time.

_Ban._ At your kind'st leisure.

_Macb._ If you shall cleave to my consent, when 'tis,
It shall make honour for you.

_Ban._ So I lose none
In seeking to augment it, but still keep
My bosom franchised and allegiance clear,
I shall be counsell'd.

_Macb._ Good repose the while!

_Ban._ Thanks, sir: the like to you!

Macbeth's first idea is, apparently, simply to free himself from any
suspicion which the discovery of the murder might suggest, by showing
himself, just before it, quite indifferent to the predictions, and
merely looking forward to a conversation about them at some future time.
But why does he go on, 'If you shall cleave,' etc.? Perhaps he foresees
that, on the discovery, Banquo cannot fail to suspect him, and thinks it
safest to prepare the way at once for an understanding with him (in the
original story he makes Banquo his accomplice _before_ the murder).
Banquo's answer shows three things,--that he fears a treasonable
proposal, that he has no idea of accepting it, and that he has no fear
of Macbeth to restrain him from showing what is in his mind.

Duncan is murdered. In the scene of discovery Banquo of course appears,
and his behaviour is significant. When he enters, and Macduff cries out
to him,

O Banquo, Banquo,
Our royal master's murdered,

and Lady Macbeth, who has entered a moment before, exclaims,

Woe, alas!
What, in our house?

his answer,

Too cruel anywhere,

shows, as I have pointed out, repulsion, and we may be pretty sure that
he suspects the truth at once. After a few words to Macduff he remains
absolutely silent while the scene is continued for nearly forty lines.
He is watching Macbeth and listening as he tells how he put the
chamberlains to death in a frenzy of loyal rage. At last Banquo appears
to have made up his mind. On Lady Macbeth's fainting he proposes that
they shall all retire, and that they shall afterwards meet,

And question this most bloody piece of work
To know it further. Fears and scruples[235] shake us:
In the great hand of God I stand, and thence
Against the undivulged pretence[236]