'Profitable' in the Bible

Can a man be profitable unto God, as he that is wise may be profitable unto himself?

If the iron be blunt, and he do not whet the edge, then must he put to more strength: but wisdom is profitable to direct.

Who hath formed a god, or molten a graven image that is profitable for nothing?

Then I went to Euphrates, and digged, and took the girdle from the place where I had hid it: and, behold, the girdle was marred, it was profitable for nothing.