Gayatri is from the Rig Veda of the Hindu culture.
Meaning:
The beginning, middle and end of all beings (OM),
The Illuminator of the Earth, Interspace and Heavens,1
I meditate upon That Great Venerable Adorable Sun.
May that self-luminous, radiant and divine Light,
illumine and inspire my intellect in the right direction.
1 Symbolically they mean the Waking, Dream and Deep Sleep states.
The Gayatri mantra in Devanagari:
ॐ भूर्भुवः स्वः ।
तत्स॑वि॒तुर्वरेण्यं॒
भर्गो॑ दे॒वस्य॑ धीमहि ।
धियो॒ यो नः॑ प्रचो॒दया॑त् ॥
om bhūr bhuvaḥ svaḥ
tát savitúr váreṇyaṃ
bhárgo devásya dhīmahi
dhíyo yó naḥ prachodayāt
– Rig Veda (Mandala 3.62.10)
