Pure devotion means asking Krishna only to engage you in His service, never for material profit or gain.Listen — Srila Prabhupada Uvaca
Initiation Lecture [partially recorded] — July 2, 1971, Los Angeles 710702IN-LOS ANGELES [06:32 Minutes] Initiation_710702IN-LOS ANGELES Prabhupāda: ...interested in material profit by devotional service, he is not fit at all to enter into the devotional service. Devotional... There are... Everyone is trying to become happier—the karmīs, jñānīs, yogīs, devotees—because in the material world there is no happiness.
So the karmīs are trying to be happier to increase their sense gratification. So one man has got hundred dollars' income. He is trying to be happy, more happy, by increasing the income to a thousand dollars, because his sense gratification is not sufficient in one hundred dollars. He wants thousand dollars. So if one takes to devotional service that "My income is hundred dollars.
Kṛṣṇa, give me thousand dollars," so this is not pure devotion. Kṛṣṇa can give. Why thousand? Millions of dollars He can give.
But anyone who asks from Kṛṣṇa for this material benefit, he is not a pure devotee. And unless one is pure devotee, he cannot enter into the kingdom of God. By devotional service if you want material prosperity, Kṛṣṇa can give you. Kṛṣṇa can...
Whatever you want, Kṛṣṇa can give you. But that is not pure devotion. Dhruva Mahārāja went to obtain his father's kingdom in the beginning, but at the end he said that "I don't want." That is the benefit. If anyone has got any desire for material benefit and takes to Kṛṣṇa consciousness, Kṛṣṇa can give him. But the benefit is that one day he'll come to the stage he'll ask nothing from the Lord.
Whereas if anyone goes to demigods to ask some material profit, he will get, but it will be finished, and he'll never come to the stage of transcendental platform that he has no material necessities. So similarly, Kṛṣṇa's name, we should not try to exact some material profit by chanting Hare Kṛṣṇa mantra. That is not pure devotion. Sarva... What is called?
Sarvopādhi-vinirmuktam [Cc. Madhya 19.170]. Anyābhilāṣitā-śūnyam [Brs. 1.1.11(1)]. We shall simply aspire to serve Kṛṣṇa.