Therefore, O King, endeavor with all your might to fix the Supreme Lord Keśava within your heart. Maintain this concentration upon the Lord, and at the time of death you will certainly attain the supreme destination.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तस्मात्सर्वात्मना राजन् हृदिस्थं कुरु केशवम् । म्रियमाणो ह्यवहितस्ततो यासि परां गतिम्
tasmātsarvātmanā rājan hṛdisthaṃ kuru keśavam | mriyamāṇo hyavahitastato yāsi parāṃ gatim
SB 12.3.49