Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 13
Sanskrit:
अप्रमत्तोऽनुयुञ्जीत मनो मय्यर्पयञ्छनै: ।अनिर्विण्णो यथाकालं जितश्वासो जितासन: ॥ १३ ॥
ITRANS:
apramatto ’nuyuñjītamano mayy arpayañ chanaiḥanirviṇṇo yathā-kālaṁjita-śvāso jitāsanaḥ
Translation:
A person should be attentive and grave and never lazy or morose. Mastering the yoga procedures of breathing and sitting properly, one should practice fixing the mind on Me at dawn, noon and sunset, and thus gradually the mind should be completely absorbed in Me.