ŚVETĀŚVATARA UPANISHAD · 1.15

तिलेषु तैलं दधनीव सर्पिर् आपः स्रोतःस्व् अरणीषु चाग्निः ।
एवम् आत्मा आत्मनि गृह्यते ऽसौ सत्येनैनं तपसा यो ऽनुपश्यति ॥

tileṣu tailaṃ dadhanīva sarpir āpaḥ srotaḥsv araṇīṣu cāgniḥ ।
evam ātmā ātmani gṛhyate ’sau satyenainaṃ tapasā yo ’nupaśyati ॥

As oil in seeds, as butter in cream, as water in (dry) river-beds, as fire in wood, so is the Self seized within the self, if man looks for him by truthfulness and penance;