'Expense' in the Bible

Brothers, I have applied all this to Apollos and myself for your benefit, so that you may learn from us not to go beyond what the Scriptures say. Then you will stop boasting about one person at the expense of another.

Who ever goes to war at his own expense? Who plants a vineyard and does not eat any of its grapes? Or who takes care of a flock and does not drink any of its milk?