Gayatri Mantra from RigVeda

Tat Savitur Varenyam
Bhargo Devasya Dheemahi
Dhiyo Yo Na Prachodayaat!

तत सवितुर वरेण्यम
भर्गो देवस्य धीमहि
धियो यो न प्रचोदयात!

We meditate on the brilliant light of the creator. Who has created the Universe. Who is worthy of Worship. Who is the embodiment of Knowledge and Light. Who is the remover of all Sin and Ignorance. May He enlighten our intellect.

- Gayatri Mantra from RigVeda 3.62.10 (also Samaveda verse 1462)

Note that this original, pristine form of the revered Gayatri does not contain the currently used first line which is:

AUM Bhuh Bhuvah Swaha

ॐ भू: भुवः स्वः

This invocation was added at a much later date ~ in the Upanishads.