Numbers 19:16-22

16 If any touch a person who has been killed or has died a natural death outdoors or if any touch a human bone or a grave, they become unclean for seven days.
17 To remove the uncleanness, some ashes from the red cow which was burned to remove sin shall be taken and put in a pot, and fresh water added.
18 In the first case, someone who is ritually clean is to take a sprig of hyssop, dip it in the water, and sprinkle the tent, everything in it, and the people who were there. In the second case, someone who is ritually clean is to sprinkle the water on those who had touched the human bone or the dead body or the grave.
19 On the third day and on the seventh the person who is ritually clean is to sprinkle the water on the unclean persons. On the seventh day he is to purify those, who, after washing their clothes and pouring water over themselves, become ritually clean at sunset.
20 Those who have become ritually unclean and do not purify themselves remain unclean, because the water for purification has not been thrown over them. They defile the Lord's Tent and will no longer be considered God's people.
21 You are to observe this rule for all time to come. The person who sprinkles the water for purification must also wash his clothes; anyone who touches the water remains ritually unclean until evening.
22 Whatever an unclean person touches is unclean, and anyone else who touches it remains unclean until evening.
Scripture taken from the Good News Translation - Second Edition, Copyright 1992 by American Bible Society. Used by Permission.