Kautilya's Arthashastra 8.5.9

8.5.9

kalatragarbhyantaḥśalyayoḥ kalatragarbhi unmucya kalatraṃ yudhyeta, nāntaḥśalyam antaramitram //

Of soldiers who are either fond of their wives or are under an enemy, those who are fond of their wives may be taken to fight after separating them from their wives; but not those who are under an enemy, and are, therefore, like internal enemies.