42
Śrīmad-Bhāgavatam
[Canto 9, Ch. 18]
śrī-yadur uvāca 
  notsahe jarasā sthātum 
  antarā prāptayā tava 
  aviditvā sukhaṁ grāmyaṁ 
  vaitṛṣṇyaṁ naiti pūruṣaḥ
śrī-yaduḥ uvāca—Yadu, the eldest son to Yayāti, replied;  na utsahe —I am not enthusiastic;  jarasā —with your old age and invalidity;  sthātum —to remain;  antarā —while in youth;  prāptayā —accepted;  tava —your;  aviditvā —without experiencing;  sukhaṁ —happiness;  grāmyaṁ —material or bodily;  vaitṛṣṇyaṁ —indifference to material enjoyment;  na —does not;  eti —attain;  pūruṣaḥ —a person.
TRANSLATION
Yadu replied:  My dear father, you have already achieved old age, although you also were a young man. But I do not welcome your old age and invalidity, for unless one enjoys material happiness, one cannot attain renunciation.
PURPORT
Renunciation of material enjoyment is the ultimate goal of human life. Therefore the  varṇāśrama  institution is most scientific. It aims at giving one the facility to return home, back to Godhead, which one cannot do without completely renouncing all connections with the material world. Śrī Caitanya Mahāprabhu said,  niṣkiñcanasya bhagavad-bhajanonmukhasya : one who wants to go back home, back to Godhead, must be  niṣkiñcana , free from all affinity for material enjoyment.  Brahmaṇy upaśamāśrayam : unless one is fully renounced, one cannot engage in devotional service or stay in Brahman. Devotional service is rendered on the Brahman platform. Therefore, unless one attains the Brahman platform, or spiritual platform, one cannot engage in devotional service; or, in other words, a person engaged in devotional service is already on the Brahman platform.
māṁ ca yo 'vyabhicāreṇa 
  bhakti-yogena sevate