Heat the oil in a large skillet over medium heat. Add the garlic and cook, stirring occasionally, until soft, 1 to 2 minutes.
Add the beans, oregano, 1/2 cup water, 3/4 teaspoon salt, and 1/2 teaspoon pepper. Simmer, stirring occasionally, until the beans are heated through, about 4 minutes.
Stir in the scallions and serve.