'Necessary' in the Bible

For it is not necessary for me to write you about this service to the saints,

Therefore I thought it necessary to urge these brothers to go to you in advance and to arrange ahead of time the generous contribution you had promised, so this may be ready as a generous gift and not as something you feel forced to do.

It is necessary to go on boasting. Though it is not profitable, I will go on to visions and revelations from the Lord.