Kautilya's Arthashastra 7.2.4

7.2.4

dvaidhībhāvasaṃśrayayor dvaidhībhāvaṃ gacchet //

The same holds good in the case of neutrality and war. Of the two (forms of policy), double policy and alliance, double policy (i.e., making peace with one and waging war with another) is preferable; for whoever adopts the double policy enriches himself, being ever attentive to his own works, whereas an allied king has to help his ally at his own expense.