|dog in the manger|
|a. a person who prevents others from using something he has no use for|
|b. (as modifier): a dog-in-the-manger attitude|
A person who spitefully refuses to let someone else benefit from something for which he or she has no personal use: “We asked our neighbor for the fence posts he had left over, but, like a dog in the manger, he threw them out rather than give them to us.” The phrase comes from one of Aesop's fables, about a dog lying in a manger full of hay. When an ox tries to eat some hay, the dog bites him, despite the fact that the hay is of no use to the dog.
dog in the manger
One who prevents others from enjoying something despite having no use for it. For example, Why be a dog in the manger? If you aren't going to use those tickets, let someone else have them. This expression alludes to Aesop's fable about a snarling dog that prevents horses from eating fodder that is unpalatable to the dog itself. [Mid-1500s]