To the sons of Gershom, according to their families, out of the tribe of Issachar, and out of the tribe of Asher, and out of the tribe of Naphtali, and out of the tribe of Manasseh in Bashan, thirteen cities.
God had given the special privilege of being priests to Aaron and his sons as a gracious blessing. Normally the first-born son acted as priest of the family in the ancient Near East. This was one of the privileges of the birthright. Reuben had forfeited this, too, by his sin.