It happened the same night, that Yahweh said to him, Take your father's bull, even the second bull seven years old, and throw down the altar of Baal that your father has, and cut down the Asherah that is by it;
What is commanded here is that Gideon should take two bullocks (which would be required in the work of demolition and in the building of the altar to Jehovah), including the FAT one, which was probably being reserved for a sacrifice.