1 Samuel 6:8-11 NIV
Take the ark of the LORD and put it on the cart, and in a chest beside it put the gold objects you are sending back to him as a guilt offering. Send it on its way, but keep watching it. If it goes up to its own territory, toward Beth Shemesh, then the LORD has brought this great disaster on us. But if it does not, then we will know that it was not his hand that struck us but that it happened to us by chance.”
So they did this. They took two such cows and hitched them to the cart and penned up their calves. They placed the ark of the LORD on the cart and along with it the chest containing the gold rats and the models of the tumors.
NIV: New International Version