1184
Śrīmad-Bhāgavatam
[ Canto 3, Ch. 28 ]
vāyv-agnibhyām yathā loham dhmātam tyajati vai malam
manaḥ—the mind; acirāt—soon; syāt—can be; virajam—free from disturbances; jita-śvāsasya—whose breathing is controlled; yoginaḥ—of the yogī; vāyu-agnibhyām—by air and fire; yathā—just as; loham—gold; dhmātam—fanned; tyajati—becomes freed from; vai—certainly; malam—impurity.
TRANSLATION
The yogīs who practice such breathing exercises are very soon freed from all mental disturbances, just as gold, when put into fire and fanned with air, becomes free from all impurities.
PURPORT
This process of purifying the mind is also recommended by Lord Caitanya; He says that one should chant Hare Kṛṣṇa. He says further,  param vijayate : “All glories to Śrī Kṛṣṇa  saṅkīrtana! ” All glories are given to the chanting of the holy names of Kṛṣṇa because as soon as one begins this process of chanting, the mind becomes purified.  Ceto-darpaṇa-mārjanam : by chanting the holy name of Kṛṣṇa one is cleansed of the dirt that accumulates in the mind. One can purify the mind either by the breathing process or by the chanting process, just as one can purify gold by putting it in a fire and fanning it with a bellows.
TEXT 11
शणायामेदहेरोषान्धारणामिश्र किल्बिषान् । प्रत्याहारेण संसर्गान्ध्यानेनानीश्वरान् गुणान् ॥१॥
prāṇāyāmair dahed doṣān dhāraṇābhiś ca kilbiṣān pratyāhāreṇa saṁsargān dhyānenānīśvarān guṇān
prāṇāyāmaiḥ—by practice of prāṇāyāma; dahet—one can eradicate; doṣān—contaminations; dhāraṇābhiḥ—by concentrating the mind; ca—and; kilbiṣān—sinful activities; pratyāhāreṇa—by restraining the senses;