"In the Padma Purāṇa, there is a nice statement praising the service of the Vaiṣṇavas or devotees. In that scripture Lord Śiva tells Pārvatī, 'My dear Pārvatī, there are different methods of worship, and out of all such methods the worship of the Supreme Person is considered to be the highest. But even higher than the worship of the Lord is the worship of the Lord's devotees.'
A similar statement is in the Third Canto, 7th Chapter, 19th verse, of the Śrīmad-Bhāgavatam: 'Let me become a sincere servant of the devotees because by serving them one can achieve unalloyed devotional service unto the lotus feet of the Lord. The service of devotees diminishes all miserable material conditions and develops within one a deep devotional love for the Supreme Personality of Godhead.'
In the Skanda Purāṇa there is a similar statement: 'Persons whose bodies are marked with tilaka, symbolizing the conchshell, wheel, club and lotus—and who keep the leaves of tulasī on their heads, and whose bodies are always decorated with gopī-candana—even seen once, can help the seer be relieved from all sinful activities.'
A similar statement is found in the First Canto, 19th Chapter, 30th verse, of the Śrīmad-Bhāgavatam: 'There is no doubt about one's becoming freed from all reactions to sinful activities after visiting a devotee or touching his lotus feet or giving him a sitting place. Even by remembering the activities of such Vaiṣṇavas, one becomes purified, along with his whole family. And what, then, can be said of rendering direct service to him?'
In the Ādi Purāṇa there is the following statement by Lord Kṛṣṇa Himself, addressed to Arjuna: 'My dear Pārtha, one who claims to be My devotee is not so. Only a person who claims to be the devotee of My devotee is actually My devotee.' No one can approach the Supreme Personality of Godhead directly. One must approach Him through His pure devotees. Therefore, in the system of Vaiṣṇava activities, the first duty is to accept a devotee as spiritual master and then to render service unto him."
(Nectar of Devotion, Chapter 12)