'Purification offering' in the Bible

A clean man will gather the ashes of the heifer, and he will put [them] in a clean {place outside the camp}; it will be for the community of the {Israelites} as a requirement for waters of impurity; it [is] a purification [offering].

For the unclean [person] they will take from the powder of the {burnt purification offering}, and they will put running water into a container.