what is Macbeth's lie to banquo about the whiches' perdictions?

In Act II scene 1 Macbeth lies to Banquo about his thoughts since their meeting with the witches -

BANQUO:I dreamt last night of the three weird sisters:

To you they have show'd some truth.

MACBETH I think not of them:

Macbeth has considered deeply the predictions which were made to them. In fact, he has already conspired with his wife to kill King Duncan, and considered how he is to be rid of Duncan's newly cited heir, Malcolm.