The term is not in scripture, the general concept could be drawn from a few things paul said, one being what the brother below just quoted.
However, I disagree with the phrase at it's core, due to the fact that grace cannot "run out", it is new every morning as the psalmist said.
People are supposed to hear from the Lord, and follow daily the direction of the Holy Spirit. If they leave a ministry, it should be because God told them to, not because they are tired, weary, or worn out. But if they began the ministry, it should also be because God told them to. If the Lord did not, then their labor is in vain, and their end will be to be totally worn out from their own labor instead of Christ's.