Now you have decided to undertake the mystic process of meditation under the instruction of your mother, just to achieve the mercy of the Lord, but in my opinion such austerities are not possible for any ordinary man. It is very difficult to satisfy the Supreme Personality of Godhead.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
अथ मात्रोपदिष्टेन योगेनावरुरुत्ससि । यत्प्रसादं स वै पुंसां दुराराध्यो मतो मम
atha mātropadiṣṭena yogenāvarurutsasi | yatprasādaṃ sa vai puṃsāṃ durārādhyo mato mama
SB 4.8.30