Dangle a carrot in front of (one) phrase
To try to coax someone into doing something by promising them a reward.
Whenever I want my wife to clean the house, I have to dangle a carrot in front of her.
When I was in primary school, my mom used to dangle a carrot in front of me to achieve the highest score in my class.
Stop dangling a carrot in front of me! I told you I wouldn't help you no matter what you gave me.
The verb "dangle" must be conjugated according to its tense.
This phrase comes from the idea of attaching a carrot to a stubborn donkey so that the carrot dangles about two feet in front of the donkey's face. As the carrot is just out of reach and the donkey is fond of carrots the donkey will move forward. The same principle works with people.