Yōga Sūtra 3.25

बलेषु हस्तिबलादीनि।

balēṣu hastibalādīni।

[बलेषु हस्ति बलादीनि।
balēṣu = by strength; hasti = elephant; balādīni = gains strength;]

By (samyama on) strength, one gains the strength of an elephant.