Agni Purana 241.37

241.37

mahāsaṅkulayuddheṣu saṃśrayeranmataṅgajaṃ /
aśvasya pratiyoddhāro bhaveyuḥ puruṣāstrayaḥ //

In massive melee combats, they should take shelter behind an elephant. / There should be three men as combatants against a horse;