How does Duncan recompense Macbeth and Banquo?
Here's the part of the play you should be looking at. Duncan has just been told that the treacherous Thane of Cawdor repented on his death bed, and he is commenting regretfully on Cawdor's treachery as Macbeth himself comes in.
There's no art
To find the mind's construction in the face:
He was a gentleman on whom I built
An absolute trust.
Enter MACBETH, BANQUO, ROSS, and ANGUS
O worthiest cousin!
The sin of my ingratitude even now
Was heavy on me: thou art so far before
That swiftest wing of recompense is slow
To overtake thee. Would thou hadst less deserved,
That the proportion both of thanks and payment
Might have been mine! only I have left to say,
More is thy due than more than all can pay.
It is some irony, isn't it, that Macbeth (who has already had "black and deep desires", presumably to kill the king) enters just as Duncan deplores the fact that you can't judge a book by its cover? Macbeth's face is already hiding a few treasonous secrets of its own!
Duncan in this speech expresses his gratitude to Macbeth and Banquo - and Macbeth, of course, we know is to be made Thane of Cawdor as a reward for his battle deeds. Shakespeare never specifies precisely what recompense Banquo receives, though we are told in this scene that he "no less deserves". Clearly, though, the role of Thane of Cawdor, is going to remain a problem one for Duncan!