act 2 scence 2

This is a biblical reference in ehich Hamlet compares Polonius to Jephthah. Jephthah promises God a burnt sacrifice of the first person to appear at his door in order that he might be insured victory over the Ammonites. Unfortunately, his virgin daughter appears and is the first to cross the threshold. 

Hamlet compares Polonius to Jephthah, in that he is willing to sacrifice Ophelia to gain what he desires. The irony comes from the way in which Hamlet insults the man, as the insults he hurls are true about himself also.