यथाशास्त्रमुपास्यस्य अर्थस्य विषयीकरणेन सामीप्यमुपगम्य तैलधारावत्समानप्रत्ययप्रवाहेण दीर्घकालं यतासनं ततुपासनमाचक्षते ।
yathā-śāstram upāsyasya arthasya viṣayīkaraṇena sāmīpyam upagamya taila-dhārāvat samāna-pratyaya-pravāheṇa dīrgha-kālaṁ yat āsanaṁ tat upāsanam ācakṣate |
(Śaṅkarācārya’s ṭīkā on Śrīmad Bhagavad-gītā: 12.3)
“Approaching the proximity of the entity to be worshipped as per the śāstra by making it an object and dwelling [upon it] for a long time with a flow of singular thought like a stream of oil—this is called upāsana.”