'Necessity' in the Bible

I think then that this is good, on account of the present necessity, that it is good for a man to remain so as he is.

For if I announce the glad tidings, I have nothing to boast of; for a necessity is laid upon me; for it is woe to me if I should not announce the glad tidings.

each according as he is purposed in his heart; not grievingly, or of necessity; for God loves a cheerful giver.

but I have wished to do nothing without thy mind, that thy good might not be as of necessity but of willingness:

For, the priesthood being changed, there takes place of necessity a change of law also.

shepherd the flock of God which is among you, exercising oversight, not by necessity, but willingly; not for base gain, but readily;