Kautilya's Arthashastra 5.3.36

5.3.36

teṣu rājā nityayuktaḥ syāt, abhīkṣṇaṃ caiṣāṃ śilpadarśanaṃ kuryāt //

Footmen, horses, chariots, and elephants shall be given necessary training in the art of war at sunrise, on all days but those of conjunction (of planets). on these occasions of training, the king shall ever be present and witness their exercise.