Nevertheless he that standeth stedfast in his heart, having no necessity, but hath power over his own will, and hath so decreed in his heart that he will keep his virgin, doeth well.
Stedfast - not to be turned from his purpose by obloquy.
Having no necessity - arising from the natural inclinations of the daughter.
Power over his own will - when, owing to his daughter's will not opposing him, he has power to effect his will.
Decreed - determined.