Charles Ellicott Commentary Judges 12:9

"And he had thirty sons; and thirty daughters he sent abroad, and thirty daughters he brought in from abroad for his sons. And he judged Israel seven years." — Judges 12:9 (ASV)

Thirty sons, and thirty daughters. —Implying polygamy, wealth, and state (Judges 8:30).

Whom he sent abroad —i.e., whom he gave in marriage “out of his house” (Vulgate, quas emittens foras maritis dedit). The only reason for recording the marriage of his sons and daughters is to show that he was a great man, and sought additional influence by intermarriages with other families. It showed no little prosperity that he lived to see his sixty children married.