Bhagavad-gītā 6.34
BG 6.34
Open the full passageचञ्चलं हि मनः कृष्ण प्रमाथि बलवद् दृढम् । तस्याहं निग्रहं मन्ये वायोरिव सुदुष्करम् ॥३४॥
Sanskrit
cañcalaṁ hi manaḥ kṛṣṇa pramāthi balavad dṛḍham tasyāhaṁ nigrahaṁ manye vāyor iva su-duṣkaram
Translation
For the mind is restless, turbulent, obstinate and very strong, O Kṛṣṇa, and to subdue it, I think, is more difficult than controlling the wind.