+ Positive Mitzvah
A Kohen to defile himself for his close relatives.
“For his mother, his father, his son, his daughter and his brother” Vayikra 21: 2
“and for his unmarried sister ……shall he contaminate/defile himself” Vayikra 21:3
Although a Kohen is forbidden to defile himself for other deceased, for his close relatives he has an obligation to be defiled also for
His wife whom he married.
His brother and sister being specifically from the same father.
Women are not required to be defiled for close relatives, rather they can decide this for themselves, however they must observe the period of mourning.
This mitzvah of the mourning period is required by all Jews to be observe for each of the seven relations, as listed above.
The first day is according to the Torah and the remaining days of mourning is from the Rabbis.
This applies in all places at all times