Preheat the oven to 375 degrees F (190 degrees C). Grease and flour a 8x4-inch loaf pan.
Beat butter and sugar together in a large bowl until light and fluffy. Add sour cream and eggs; mix well. Add flour and a pinch of soda, mix until just incorporated. Pour batter into prepared pan.
Bake in the preheated oven until a toothpick inserted into center of cake comes out clean, about 1 hour.