CC Madhya 9.258

prabhu kahe,śāstre kahe śravaṇa-kīrtana
kṛṣṇa-prema-sevā-phalera ‘parama-sādhana’
Word for word: 
prabhu kahe — Lord Śrī Caitanya Mahāprabhu said; śāstre kahe — in the śāstra it is said; śravaṇa-kīrtana — the process of chanting and hearing; kṛṣṇa-prema-sevā — of loving service to Lord Kṛṣṇa; phalera — of the result; parama-sādhana — best process of achievement.
Translation: 
Śrī Caitanya Mahāprabhu said, “According to the verdict of the śāstras, the process of hearing and chanting is the best means to attain loving service to Kṛṣṇa.
Purport: 

According to the Tattvavādīs, the best process for achieving the highest goal of life is to execute the duties of the four varṇas and āśramas. In the material world, unless one is situated in one of the varṇas (brāhmaṇa, kṣatriya, vaiśya or śūdra) one cannot manage social affairs properly to attain the ultimate goal. One also has to follow the principles of the āśramas (brahmacarya, gṛhastha, vānaprastha and sannyāsa), since these principles are considered essential for the attainment of the highest goal. In this way the Tattvavādīs establish that the execution of the principles of varṇa and āśrama for the sake of Kṛṣṇa is the best way to attain the topmost goal. The Tattvavādīs thus established their principles in terms of human society. Śrī Caitanya Mahāprabhu, however, differed when He said that the best process is hearing and chanting about Lord Viṣṇu. According to the Tattvavādīs, the highest goal is returning home, back to Godhead, but in Śrī Caitanya Mahāprabhu’s opinion the highest goal is attaining love of Godhead, in either the material world or the spiritual world. In the material world this is practiced according to śāstric injunction, and in the spiritual world the real achievement is already there.