226
Śrīmad-Bhāgavatam
[Canto 7, Ch. 15]
master is as good as the Supreme Personality of Godhead, and therefore one who is very serious about spiritual advancement must regard the spiritual master in this way. Even a slight deviation from this understanding can create disaster in the disciple's Vedic studies and austerities.
TEXT 28
षड्गर्मसंयमैकान्ताः सर्वा नियमचोदनाः । तदन्ता यदि नो योगानावहेयुः श्रमावहाः ॥२८॥
ṣaḍ-varga-saṁyamaikāntāḥ sarvā niyama-codanāḥ tad-antā yadi no yogān āvaheyuḥ śramāvahāḥ
ṣaṭ-varga —the six elements, namely the five working senses and the mind;  saṁyama-ekāntāḥ —the ultimate aim of subjugating;  sarvāḥ —all such activities;  niyama-codanāḥ —the regulative principles further meant for controlling the senses and mind;  tat-antāḥ —the ultimate goal of such activities;  yadi —if;  no —not;  yogān —the positive link with the Supreme;  āvaheyuḥ —did lead to;  śrama-āvahāḥ —a waste of time and labor.
TRANSLATION
Ritualistic ceremonies, regulative principles, austerities and the practice of yoga are all meant to control the senses and mind, but even after one is able to control the senses and mind, if he does not come to the point of meditation upon the Supreme Lord, all such activities are simply labor in frustration.
PURPORT
One may argue that one may achieve the ultimate goal of life—realization of the Supersoul—by practicing the  yoga  system and ritualistic performances according to the Vedic principles, even without staunch devotion to the spiritual master. The actual fact, however, is that by practicing  yoga  one must come to the platform of meditating upon the Supreme Personality of Godhead. As stated in the scriptures,