1 Samuel 6:7
Now therefore make a new cart, and take two milch kine, on which there hath come no yoke, and tie the kine to the cart, and bring their calves home from them: Now therefore make a new cart, and take two milch kine, on which there hath come no yoke, and tie the kine to the cart, and bring their calves home from them:
The priests and diviners devised that a new cart be made and two milch cows on which no yoke had ever come be tied to it, while their calves were kept at home away from them. The arrangement was set as a test of whether the God of Israel had caused the afflictions upon the Philistines or whether it had been chance. Since the cows would naturally stay with or return to their calves, their leaving them and going directly toward Beth-shemesh would prove divine causation.
The instructions were carried out, with the ark set upon the cart together with a gold trespass offering. Though lowing for their calves, the cows turned from their young and went straight to Beth-shemesh without human guidance. Their direct course demonstrated that an unseen divine power guided them and that the divine presence accompanied the ark and brought it safely to its appointed place. At Beth-shemesh the Israelites received the ark and offered the cows to the Lord.
The Lord directed the unyoked cows to leave their calves behind and devote themselves to carrying the ark to its proper place. This shows that God can guide His sacred work to its place without human hands trying to control or steady it.