Charles Ellicott Commentary Leviticus 21:2

"except for his kin, that is near unto him, for his mother, and for his father, and for his son, and for his daughter, and for his brother," — Leviticus 21:2 (ASV)

But for his kin, that is near to him. —There are, however, seven exceptions to the general rule. According to the administrators of the Law during the Second Temple, the phrase his kin that is near to him, or rather, his flesh that is near to him (compare Leviticus 18:6 with Genesis 2:24), denotes “wife.” Hence the Chaldee version of Jonathan renders it, “but for a wife who is of kin to his flesh.”

For his mother, and for his father.— This is the second of the three instances in the Bible where the mother is mentioned before the father . The Jewish canonists, who call attention to this unusual phrase, explain it by saying that she is placed first because the son’s qualifications for the priesthood depend more on his having a good mother .

This will be readily understood when it is kept in mind that the regulations about the woman whom a priest was allowed to marry during the Second Temple were of the most stringent nature, and that the slightest infringement of them disqualified the son for performing sacerdotal functions. Thus, the daughter of a foreigner or of a released captive was forbidden to the priest, and when a city was besieged and taken by the enemy, all the wives of the priests had to be divorced for fear that they had suffered violence.