CC Madhya 13.140
yatna kari, nāri kāḍhibāre
tāre dhyāna śikṣā karāha, loka hāsāñā māra,
sthānāsthāna nā kara vicāre
Śrīla Rūpa Gosvāmī says in his Bhakti-rasāmṛta-sindhu (1.1.11):
ānakūlyena kṛṣṇānu- śīlanaṁ bhaktir uttamā
For a pure devotee, there is no scope for indulgence in mystic yoga practice or the cultivation of speculative philosophy. It is indeed impossible for a pure devotee to engage his mind in such unwanted activities. Even if a pure devotee wanted to, his mind would not allow him to do so. That is a characteristic of a pure devotee — he is transcendental to all fruitive activity, speculative philosophy and mystic yoga meditation. The gopīs therefore expressed themselves as follows.