Mahabharata 4.42.26

4.42.26

ācāryā vai kāruṇikāḥ prājñāścāpāyadarśinaḥ |
naite mahābhaye prāpte saṃpraṣṭavyāḥ kathaṃcana || 26 ||

All this (on Drona's part), therefore, is due only to either the desire of doing good to Arjuna or to his wrath and hatred towards us. Preceptors are wise, and sinless, and very kind to all creatures. They, however, should never be consulted at times of peril. It is in luxurious palaces, and assemblies and pleasure-gardens, that learned men, capable of making speeches, seem to be in their place. Performing many wonderful things, in the assembly, it is there that learned men find their place, or even there where sacrificial utensils and their proper placing and washing are needed. In a knowledge of the lapses of others, in studying the characters of men, in the science of horses and elephants and cars, in treating the diseases of asses and camels and goats and sheeps and kine, in planning buildings and gateways, and in pointing out the defects of food and drink, the learned are truly in their own sphere. Disregarding learned men that extol the heroism of the foe, make ye such arrangements that the foe may be destroyed. Placing the kine securely, array the troops in order of battle. Place guards in proper places so that we may fight the foe.'"