SB 1.15.39
mathurayam tatha vajram
surasena-patim tatah
prajapatyam nirupyestim
agnin apibad isvarah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Then he posted Vajra, the son of Aniruddha [grandson of Lord Krsna], at Mathura as the King of Surasena. Afterwards Maharaja Yudhisthira performed a Prajapatya sacrifice and placed in himself the fire for quitting household life.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Maharaja Yudhisthira, after placing Maharaja Pariksit on the imperial throne of Hastinapura, and after posting Vajra, the great-grandson of Lord Krsna, as the King of Mathura, accepted the renounced order of life. The system of four orders of life and four castes in terms of quality and work, known as varnasrama-dharma, is the beginning of real human life, and Maharaja Yudhisthira, as the protector of this system of human activities, timely retired from active life as a sannyasi, handing over the charge of the administration to a trained prince, Maharaja Pariksit. The scientific system of varnasrama-dharma divides the human life into four divisions of occupation and four orders of life. The four orders of life as brahmacarya, grhastha, vanaprastha and sannyasa are to be followed by all, irrespective of the occupational division. Modern politicians do not wish to retire from active life, even if they are old enough, but Yudhisthira Maharaja, as an ideal king, voluntarily retired from active administrative life to prepare himself for the next life. Everyone’s life must be so arranged that the last stage of life, say at least the last fifteen to twenty years prior to death, can be absolutely devoted to the devotional service of the Lord to attain the highest perfection of life. It is really foolishness to engage oneself all the days of one’s life in material enjoyment and fruitive activities, because as long as the mind remains absorbed in fruitive work for material enjoyment, there is no chance of getting out from conditioned life, or material bondage. No one should follow the suicidal policy of neglecting one’s supreme task of attaining the highest perfection of life, namely going back home, back to Godhead.