The Gayatri mantra originated from the Rig Veda. It is also known as the poem of the Divine. The purpose of the hymn is to act as an offering of gratitude to the Sun (Savitur) and to seek enlightment.
Om Bhur Bhuvaḥ Swaḥ Tat-savitur Vareñyaṃ Bhargo Devasya Dhīmahi Dhiyo Yonaḥ Prachodayāt
Meaning: “We meditate on that most adored Supreme Lord, the creator, whose effulgence (divine light) illumines all realms (physical, mental and spiritual). May this divine light illumine our intellect.”