Act I Scene IV

Duncan is pretty impressed with Macbeth. He is happy that Macbeth was responsible for beating back the Norwegian army. He says to Macbeth ,

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.

Duncan is speaking a little in hyperbole here, but he means that Macbeth will profit from his heroic acts in war. Really , a king doesn't have to give his subjects anything, but Duncan is gracious and appreciative of Macbeth.