What did Prospero warn Ferdinand about?

Prospero warned Ferdinand that his daughter was to remain a virgin until their marriage. If Ferdinand doesn't respect this rule..... their marriage will not be a happy one.

If thou dost break her virgin knot before All sanctimonious ceremonies may With full and holy rite be ministered, No sweet aspersion shall the heavens let fall To make this contract grow, but barren hate, Sour-eyed disdain, and discord shall bestrew The union of your bed with weeds so loathly That you shall hate it both.