सैषा चतुष्पदा षड्विधा गायत्री तदेतदृचाभ्यनूक्तम् ॥ ५ ॥
In plain words
This same Gāyatrī has four feet and is sixfold. This very fact has been corroborated by a sacred verse.
Close to the Sanskrit
That this four-footed sixfold Gāyatrī, that this has been spoken of by a ṛc verse.