Numbers 6:7
Not even for his father or for his mother, for brother or sister, if they die, shall he make himself unclean, because his separation to God is on his head.
Numbers 9:6
And there were certain men who were unclean through touching a dead body, so that they could not keep the Passover on that day, and they came before Moses and Aaron on that day.
Leviticus 21:1-2
And the LORD said to Moses, "Speak to the priests, the sons of Aaron, and say to them: No one shall make himself unclean for the dead among his people,
Leviticus 21:10-12
"The priest who is chief among his brothers, on whose head the anointing oil is poured and who has been consecrated to wear the garments, shall not let the hair of his head hang loose nor tear his clothes.
Ezekiel 44:25
They shall not defile themselves by going near to a dead person. However, for father or mother, for son or daughter, for brother or unmarried sister they may defile themselves.