On Renunciation:

Of those then who say that they have renounced this world, and afterwards being overcome by want of faith are afraid of losing their worldly goods, a charge is given mystically in Deuteronomy. 'If any man is afraid and of a fearful heart, let him not go forth to war: let him go back and return home, lest he make the hearts of his breathen to fear as he himself is timid and frightened' (Deut.20:8). What can one want plainer than this testimony? Does not Scripture clearly prefer that they should not take on them even the earliest stages of this profession (monasticism) and its name, rather than by their persuasion and bad example turn others back from the perfection of the gospel, and weaken them by their faithless terror. And so they are bidden to withdraw from the battle with a double heart. For 'a double-minded man is unstable in all his ways' (James 1:8). And thinking, according to that Parable in the Gospel, that he who goes forth with ten thousand men against a king who comes with twenty thousand, cannot possibly fight, they should, while he is yet a great way off, ask for peace; that is, it is better for them not even to take the first step towards renunciation, rather than afterwards following it up coldly, to involve themselves in still greater dangers. For 'it is better not to vow, than to vow and not to pay' (Eccl.5:4)...And 'no man putting his hand to the plough and looking back is fit for the kingdom of God.'

St. John Cassian, The Institutes, Book VII, Chapter XV, B#60