SB 7.11.2

śrī-yudhiṣṭhira uvāca
bhagavan śrotum icchāmi
 nṛṇāṁ dharmaṁ sanātanam
varṇāśramācāra-yutaṁ
 yat pumān vindate param
Synonyms: 
śrī-yudhiṣṭhiraḥ uvāca — Mahārāja Yudhiṣṭhira inquired; bhagavan — O my lord; śrotum — to hear; icchāmi — I wish; nṛṇām — of human society; dharmam — the occupational duties; sanātanam — common and eternal (for everyone); varṇa-āśrama-ācāra-yutam — based on the principles of the four divisions of society and the four divisions of spiritual advancement; yat — from which; pumān — the people in general; vindate — can enjoy very peacefully; param — the supreme knowledge (by which one can attain devotional service).
Translation: 
Mahārāja Yudhiṣṭhira said: My dear lord, I wish to hear from you about the principles of religion by which one can attain the ultimate goal of life — devotional service. I wish to hear about the general occupational duties of human society and the system of social and spiritual advancement known as varṇāśrama-dharma.
Purport: 

Sanātana-dharma means devotional service. The word sanātana refers to that which is eternal, which does not change but continues in all circumstances. We have several times explained what the eternal occupational duty of the living being is. Indeed, it has been explained by Śrī Caitanya Mahāprabhu. Jīvera ‘svarūpa’ hayakṛṣṇera ‘nitya-dāsa’: the real occupational duty of the living entity is to serve the Supreme Personality of Godhead. Even if one prefers to deviate from this principle he remains a servant because that is his eternal position; but one serves māyā, the illusory, material energy. The Kṛṣṇa consciousness movement, therefore, is an attempt to guide human society to serving the Personality of Godhead instead of serving the material world with no real profit. Our actual experience is that every man, animal, bird and beast — indeed, every living entity — is engaged in rendering service. Even though one’s body or one’s superficial religion may change, every living entity is always engaged in the service of someone. Therefore, the mentality of service is called the eternal occupational duty. This eternal occupational duty can be organized through the institution of varṇāśrama, in which there are four varṇas (brāhmaṇa, kṣatriya, vaiśya and śūdra) and four āśramas (brahmacarya, gṛhastha, vānaprastha and sannyāsa). Thus, Yudhiṣṭhira Mahārāja inquired from Nārada Muni about the principles of sanātana-dharma for the benefit of human society.