Ezekiel 44:25-27

25They shall not go to a dead person to defile themselves; except for father or for mother, for son or for daughter, for brother or for sister who has had no husband; they may defile themselves.

26After he is cleansed [from the defilement of a corpse], seven days more shall elapse for him [before returning to the temple].

27On the day that he goes into the sanctuary, into the inner courtyard to minister in the sanctuary, he shall offer his sin offering,” says the Lord God.