Jamieson, Fausset and Brown on 1 Kings 21:7

7. Dost thou now govern the kingdom of Israel?--This is not so much a question as an exclamation--a sarcastic taunt; "A pretty king thou art! Canst not thou use thy power and take what thy heart is set upon?"

arise, and eat bread, and let thine heart be merry: I will give thee the vineyard--After upbraiding Ahab for his pusillanimity and bidding him act as a king, Jezebel tells him to trouble himself no more about such a trifle; she would guarantee the possession of the vineyard.