SB 11.10.1

śrī-bhagavān uvāca
mayoditeṣv avahitaḥ
 sva-dharmeṣu mad-āśrayaḥ
varṇāśrama-kulācāram
 akāmātmā samācaret
Word for word: 
śrī-bhagavān uvāca — the Supreme Personality of Godhead said; mayā — by Me; uditeṣu — spoken; avahitaḥ — with great care; sva-dharmeṣu — in the duties of devotional service to the Lord; mat-āśrayaḥ — one who accepts Me as shelter; varṇa-āśrama — the Vedic system of social and occupational divisions; kula — of the society; ācāram — conduct; akāma — devoid of material desires; ātmā — such a person; samācaret — should practice.
Translation: 
The Supreme Personality of Godhead said: Taking full shelter in Me, with the mind carefully fixed in the devotional service of the Lord as spoken by Me, one should live without personal desire and practice the social and occupational system called varṇāśrama.
Purport: 

In the previous chapters Lord Kṛṣṇa described through the story of an avadhūta brāhmaṇa the qualities and character of a saintly person. Now the Lord describes the practical means for achieving such a saintly position. In the Pañcarātra and other scriptures the Personality of Godhead gives instructions for executing devotional service. Similarly, in Bhagavad-gītā (4.13) the Lord says, cātur-varṇyaṁ mayā sṛṣṭaṁ guṇa-karma-vibhāgaśaḥ: “I have personally created the varṇāśrama system.” There are innumerable rules and regulations in the varṇāśrama system, and the devotee should execute those which do not contradict the process of devotional service. The term varṇa indicates different classes of human beings, some in the mode of ignorance, some in the mode of passion and some in the mode of goodness. Devotional service to the Lord is executed on the liberated platform, and therefore some injunctions for those persons in passion and ignorance may be contradictory to the regulative principles for those on the liberated platform. Therefore, under the guidance of a bona fide spiritual master who is nondifferent from the Lord, one should execute the basic principles of varṇāśrama in a way favorable for advancement in Kṛṣṇa consciousness.