In act 2, scene 2, Hamlet, pretending to be mad, says to Polonius,
O Jephthah, judge of Israel, what a treasure hadst thou!
In the book of Judges, Jephthah, a judge or leader of Israel, made a vow to God that if he won his battle over the Ammonites, he would sacrifice as a burnt offering what first came through his door when he got home. He won the battle, but unfortunately, what first came through his door was his daughter. He felt he had no choice but to sacrifice her. Hamlet is accusing Polonius of being as willing to sacrifice Ophelia to his ambitions as Jephthah was his daughter. He is also suggesting that he knows how controlling Polonius is toward Ophelia and the extent to which Ophelia will sacrifice herself to his needs. In act 1, scene 3, Polonius points out to her that she must behave first and foremost in way that "behooves" his daughter and must give him information, which she does:
You do not understand yourself so clearly
As it behooves my daughter and your honor.
What is between you? Give me up the truth.
It is also worth pointing out that the biblical book of Judges, which was more familiar to the Elizabethans than it is to us today, is a very dark book. In the Israel of Judges, as in Denmark, something is rotten. The times are out of joint, so much so that in the next book, the Israelites will beg to be given a king like the other nations around them instead of being ruled by judges.
Hamlet also likens Polonius to a fishmonger, a double entendre which has another meaning of "pimp"—meaning that he is willing to sell out his daughter for his own gain: the increased approval of Claudius