Deuteronomy 21:3-13

3 and the elders of the city which is nearest to the slain man shall take a heifer which has never been worked and which has not pulled in the yoke.
4 And the elders of that city shall bring the heifer down to a valley with running water, which is neither plowed nor sown, and shall break the heifer's neck there in the valley.
5 And the priests the sons of Levi shall come forward, for the LORD your God has chosen them to minister to him and to bless in the name of the LORD, and by their word every dispute and every assault shall be settled.
6 And all the elders of that city nearest to the slain man shall wash their hands over the heifer whose neck was broken in the valley;
7 and they shall testify, 'Our hands did not shed this blood, neither did our eyes see it shed.
8 Forgive, O LORD, thy people Israel, whom thou hast redeemed, and set not the guilt of innocent blood in the midst of thy people Israel; but let the guilt of blood be forgiven them.'
9 So you shall purge the guilt of innocent blood from your midst, when you do what is right in the sight of the LORD.
10 "When you go forth to war against your enemies, and the LORD your God gives them into your hands, and you take them captive,
11 and see among the captives a beautiful woman, and you have desire for her and would take her for yourself as wife,
12 then you shall bring her home to your house, and she shall shave her head and pare her nails.
13 And she shall put off her captive's garb, and shall remain in your house and bewail her father and her mother a full month; after that you may go in to her, and be her husband, and she shall be your wife.
Revised Standard Version of the Bible, copyright 1952 [2nd edition, 1971] by the Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.