Shatapatha Brahmana 6.3.1.14

6.3.1.14

yuktena manasā vayamiti | mana evaitadetasmai karmaṇe yuṅkte na hyuyuktena manasā kiṃ cana samprati śaknāti kartuṃ devasya savituḥ sava iti devena savitrā prasūtā ityetatsvargyāya śaktyeti yathaitena karmaṇā svargaṃ lokamiyādevametadāha śaktyeti śaktyā hi svargaṃ lokameti

[Vâg. S. XI, 2] 'With harnessed mind we,'--he thereby harnesses the mind for this work, for with unharnessed mind one cannot now do anything;--'at the impulse of the god Savitri,'--that is impelled (sped) by the god Savitri,--'with power (we strive) for the heavenly;'--'that by this holy work he may go to the heavenly world,' he thereby means to say; 'with power,' he says, for by power (energy) one goes to the heavenly world.