Here the words priya janān anusevatāṁ naḥ indicate that the Supreme Lord, the Supreme Personality of Godhead, is very favorable to devotees who act according to the instructions of His own pure devotee. In other words, one must become the servant of the servant of the servant of the Lord. If one wants to become the servant of the Lord directly, this is not as fruitful as engaging in the service of the Lord's servant. This is the direction of Śrī Caitanya Mahāprabhu, who shows us the way to become gopī-bhartuḥ pada-kamalayor dāsa-dāsānudāsaḥ (CC Madhya 13.80). One should not be proud of becoming directly the servant of the Supreme Personality of Godhead. Rather, one must seek a pure devotee, a servant of the Lord, and engage oneself in the service of such a servant. The more one becomes the servant of the servant, the more one becomes perfect in devotional service. This is also the injunction of Bhagavad-gītā: evaṁ paramparā-prāptam imaṁ rājarṣayo viduḥ (BG 4.2). One can understand the science of the Supreme Personality of Godhead simply by the paramparā system. In this regard, Śrīla Narottama dāsa Ṭhākura says, tāṅdera caraṇa sevi bhakta-sane vāsa: "Let me serve the lotus feet of the devotees of the Lord, and let me live with devotees." Janame janame haya, ei abhilāṣa. Following Narottama dāsa Ṭhākura, one should aspire to be a servant of the Lord's servant, life after life. Śrīla Bhaktivinoda Ṭhākura also sings, tumi ta' ṭhākura, tomāra kukura, baliyā jānaha more: "O my Lord, O Vaiṣṇava, please consider me your dog." One must become the dog of a Vaiṣṇava, a pure devotee, for a pure devotee can deliver Kṛṣṇa without difficulty. Kṛṣṇa se tomāra, kṛṣṇa dite pāra. Kṛṣṇa is the property of His pure devotee, and if we take shelter of a pure devotee, he can deliver Kṛṣṇa very easily. Prahlāda wants to engage in the service of a devotee, and therefore he prays to Kṛṣṇa, "My dear Lord, kindly give me the shelter of Your very dear devotee so that I may engage in his service and You may then be pleased." Mad-bhakta-pūjābhyadhikā (SB 11.19.21). The Lord says, "Engaging in the service of My devotee is better than trying to engage in My devotional service."
Another significant point in this verse is that by devotional service Prahlāda Mahārāja does not want to benefit alone. Rather, he prays to the Lord that all of us fallen souls in this material world may, by the grace of the Lord, engage in the service of His servant and thus be delivered. The grace of the Lord is not at all difficult for the Lord to bestow, and thus Prahlāda Mahārāja wants to save the whole world by spreading Kṛṣṇa consciousness.