Thematic Bible: Specially required to avoid

The Lord said to Moses, Speak to the priests [exclusive of the high priest], the sons of Aaron, and say to them that none of them shall defile himself for the dead among his people [by touching a corpse or assisting in preparing it for burial], Except for his near [blood] kin, for his mother, father, son, daughter, brother, And for his sister, a virgin, who is near to him because she has had no husband; for her he may be defiled. read more.
He shall not even defile himself, being a [bereaved] husband [his wife not being his blood kin] or being a chief man among his people, and so profane himself. The priests [like the other Israelite men] shall not shave the crown of their heads or clip off the corners of their beard or make any cuttings in their flesh. They shall be holy to their God and not profane the name of their God; for they offer the offerings made by fire to the Lord, the bread of their God; therefore they shall be holy.

Neither shall he go in where any dead body lies nor defile himself [by doing so, even] for his father or for his mother; Neither shall he go out of the sanctuary nor desecrate or make ceremonially unclean the sanctuary of his God, for the crown or consecration of the anointing oil of his God is upon him. I am the Lord.