Devibhagavatapurana 7.35.59

7.35.59

yāvanmano layaṃ yāti devyāṃ saṃvidi parvata |
tāvadiṣṭamanuṃ mantrī japahomaiḥ samabhyaset ||

The practiser must practise with Japam and Homam the Mantram till his mind be not dissolved in Me, My Consciousness. By the practice of meditating on the Mantra, the thing to be known (Brahma) is transformed into knowledge. Know this as certain, that the Mantra is futile without Yoga and the Yoga is futile without the Mantra. The Mantra and the Yoga are the two infallible means to realise Brahma. As the jar in a dark room is visible by a lamp, so this Jîvâtmâ, surrounded by Mâyâ is visible by means of Mantra to the Paramâtmâ (the Highest Self). O Best of Mountains! Thus I have described to you the Yogas with their Angas (limbs). You should receive instructions about them from the mouth of a Guru; else millions of S'âstras will never be able to give you a true realisation of the meanings of the yogas.
Here ends the Thirty-fifth Chapter of the Seventh Book on the Yoga and the Mantra Siddhi in the Mahâ Purânam S'ri Mad Devî Bhâgavatam of 18,000 verses, by Maharsi Veda Vyâsa.