1 Samuel 6:9-10

9And see, if it go up by the way of its own border to Beth-shemesh, it is he who has done us this great evil; if not, then we shall know that it is not his hand that touched us; it was a chance [that] happened to us.

10And the men did so, and took two milch kine, and tied them to the cart, and shut up their calves at home.