'Necessity' in the Bible

I suppose, therefore, this to be good because of the present necessity, that it is good for a man that the matter be thus: --

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.

For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel!

For there must of necessity be differences of opinion among you, in order that it may be plainly seen who are the men of sterling worth among you.

But quite the contrary, the parts of the body that seem to be weaker are [absolutely] necessary;