Mbh 12.57.1a

"'Bhishma said, "The king, O Yudhishthira, should always be ready for action. That king is not worth of praise who, like a woman, is destitute of exertion. In this connection, the holy Usanas has sung a Sloka, O monarch. Listen to it with attention, O king, as I recite it to thee: 'Like a snake swallowing up mice, the earth swallows up these two, the king that is averse to battle and the Brahmana that is exceedingly attached to wives and children.'[163] It behoveth thee, O tiger among kings, to bear this always in thy heart. Make peace with those foes with whom (according to the ordinance) peace should be made, and wage war with them with whom war should be waged. Be he thy preceptor or be he thy friend, he that acts inimically towards thy kingdom consisting of seven limbs, should be slain.[164] There is an ancient Sloka sung by king Marutta, agreeable to Vrihaspati's opinion, O monarch, about the duty of kings. According to the eternal provision, there is punishment for even the preceptor if he becomes haughty and disregardful of what should be done and what should not, and if he transgresses all restraints. Jadu's son, king Sagara, of great intelligence, from desire of doing good to the citizens, exiled his own eldest son Asamanjas. Asamanjas, O king, used to drown the children of the citizens in the Sarayu. His sire, therefore, rebuked him and sent him to exile. The Rishi Uddalaka cast off his favourite son Swetaketu (afterwards) of rigid penances, because the latter used to invite Brahmanas with deceptive promises of entertainment. The happiness of their subjects, observance of truth, and sincerity of behaviour are the eternal duty of kings. The king should not covet the wealth of others. He should in time give what should be given, If the king becomes possessed of prowess, truthful in speech, and forgiving in temper, he would never fall away from prosperity.