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?