Then the elders of the city nearest the victim shall take a heifer that has never been yoked or used for work,

Numbers 19:2
"This is the statute of the law that the LORD has commanded: Instruct the Israelites to bring you an unblemished red heifer that has no defect and has never been placed under a yoke.

Deuteronomy 21:2
your elders and judges must come out and measure the distance from the victim to the neighboring cities.

Deuteronomy 21:4
bring the heifer to a valley with running water that has not been plowed or sown, and break its neck there by the stream.

1 Samuel 6:7
Now, therefore, prepare one new cart with two milk cows that have never been yoked. Hitch the cows to the cart, but take their calves away and pen them up.

And it shall be, that the city which is next to the slain man, even the elders of that city shall take an heifer, which has not been worked with, and which has not drawn in the yoke;