'Work' in the Bible

having been confident of this very thing, that He who did begin in you a good work, will perform it till a day of Jesus Christ,

And if to live in the flesh is to me a fruit of work, then what shall I choose? I know not;

So that, my beloved, as ye always obey, not as in my presence only, but now much more in my absence, with fear and trembling your own salvation work out,

for God it is who is working in you both to will and to work for His good pleasure.

because on account of the work of the Christ he drew near to death, having hazarded the life that he might fill up your deficiency of service unto me.