Śatapatha Brāhmaṇa ("of a hundred paths") 6.7.2.16

6.7.2.16

viṣṇoḥ kramo 'sīti | viṣṇurhi bhūtvā kramate śatrūyato hanteti śatruyato hātra hantyānuṣṭubhaṃ canda ārohetyānuṣṭubhaṃ canda ārohati diśo 'nu vikramasveti sarvā diśo 'nu vīkṣate na praharati pādaṃ nedimāṃlokānatipraṇaśyānītyūrdhvamevāgnimudgṛhṇāti saṃ hyārohati

'Thou art Vishnu's stride,'--for in the form of Vishnu he strides;--'the slayer of the hostile,'--for he now does slay the hostile;--'mount thou the Anushtubh metre!'--the Anushtubh metre he does mount;--'stride along the quarters!'--he looks along the (four) quarters; he does not stretch forward his foot, thinking, 'Lest I lose these worlds!'--He raises the fire right up, for he ascends completely (to the top).