Śrī Caitanya-caritāmṛta - Madhya-līlā 19.151

"“According to their karma, all living entities are wandering throughout the entire universe. Some of them are being elevated to the upper planetary systems, and some are going down into the lower planetary systems. Out of many millions of wandering living entities, one who is very fortunate gets an opportunity to associate with a bona fide spiritual master by the grace of Kṛṣṇa. By the mercy of both Kṛṣṇa and the spiritual master, such a person receives the seed of the creeper of devotional service."

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Śrī caitanya-caritāmṛta Madhya 19.151