Deuteronomy 20:6
And what man is he that hath planted a vineyard, and hath not yet eaten of it? let him also go and return unto his house, lest he die in the battle, and another man eat of it. And what man is he that hath planted a vineyard, and hath not yet eaten of it? let him also go and return unto his house, lest he die in the battle, and another man eat of it.
The law required that before battle proclamation be made excusing any man who had planted a vineyard but had not yet eaten of its fruit, sending him home lest he fall in combat and another enjoy it in his place. This vineyard release stood together with releases for the builder of a new house, the man betrothed to a wife, and those who were fearful, as the customary procedure Israel was to follow on the eve of war. Gideon omitted that usual proclamation because his army was already small. The arrangement displayed tender regard for life and for domestic ties, so that no one was compelled to enter battle against his will.
So too in the work of God, those whose minds are taken up with private interests are to step back rather than remain to injure the cause by the influence of their example.