'Unprofitable' in the Bible

“Should he rebuke and argue with useless talk?Or with words in which there is no benefit?

“All have turned aside, together they have become useless;There is none who does good, no, not one.”

But avoid foolish and ill-informed and stupid controversies and genealogies and dissensions and quarrels about the Law, for they are unprofitable and useless.

Once he was useless to you, but now he is indeed useful to you as well as to me.