SB 1.15.45

sarve tam anunirjagmur
 bhrātaraḥ kṛta-niścayāḥ
kalinādharma-mitreṇa
 dṛṣṭvā spṛṣṭāḥ prajā bhuvi
Synonyms: 
sarve — all his younger brothers; tam — him; anunirjagmuḥ — left home by following the elder; bhrātaraḥ — brothers; kṛta-niścayāḥ — decidedly; kalinā — by the Age of Kali; adharma — principle of irreligion; mitreṇa — by the friend; dṛṣṭvā — observing; spṛṣṭāḥ — having overtaken; prajāḥ — all citizens; bhuvi — on the earth.
Translation: 
The younger brothers of Mahārāja Yudhiṣṭhira observed that the Age of Kali had already arrived throughout the world and that the citizens of the kingdom were already affected by irreligious practice. Therefore they decided to follow in the footsteps of their elder brother.
Purport: 

The younger brothers of Mahārāja Yudhiṣṭhira were already obedient followers of the great Emperor, and they had sufficiently been trained to know the ultimate goal of life. They therefore decidedly followed their eldest brother in rendering devotional service to Lord Śrī Kṛṣṇa. According to the principles of sanātana-dharma, one must retire from family life after half the duration of life is finished and must engage himself in self-realization. But the question of engaging oneself is not always decided. Sometimes retired men are bewildered about how to engage themselves for the last days of life. Here is a decision by authorities like the Pāṇḍavas. All of them engaged themselves in favorably culturing the devotional service of the Lord Śrī Kṛṣṇa, the Supreme Personality of Godhead. According to Svāmī Śrīdhara, dharma, artha, kāma and mokṣa, or fruitive activities, philosophical speculations and salvation, as conceived by several persons, are not the ultimate goal of life. They are more or less practiced by persons who have no information of the ultimate goal of life. The ultimate goal of life is already indicated by the Lord Himself in the Bhagavad-gītā (18.64), and the Pāṇḍavas were intelligent enough to follow it without hesitation.