The famous Gayatri mantra is found in which mandala (book) of the Rigveda?

The Gayatri mantra is found in the third mandala of the Rigveda (hymn 3.62.10).

About the Gayatri mantra:

• It is addressed to Savitri (Savitr), the sun god as the source of light and life, who inspires and enlivens.
• It is a prayer asking the god to inspire and illuminate the intellect of the worshipper.
• Its text begins "Tat savitur varenyam, bhargo devasya dhimahi, dhiyo yo nah prachodayat".
• It means, approximately: "We meditate on the glorious light of the divine Savitri; may he inspire our thoughts."
• In later times, the phrase "Om bhur bhuvah svah" was added at the beginning.
• It is composed in the "Gayatri" metre, which has three lines of eight syllables each (24 syllables in all); the mantra takes its name from this metre.

Its composer:

The third mandala is attributed to the sage Vishvamitra and his family, and the Gayatri mantra is traditionally attributed to him.

Its importance:

• It is one of the most sacred and widely recited mantras in Hinduism.
• It was taught to boys at the time of their initiation into Vedic studies.
• It is recited daily in the "Sandhyavandana" ritual at sunrise, noon and sunset.
• It is also called "Savitri" or the "Savitri mantra".
• In the 19th century, reformers such as Raja Rammohun Roy and Swami Dayananda Saraswati promoted its recitation.

About the family books of the Rigveda:

Mandalas 2 to 7 are attributed to particular families of sages:

• Mandala 2: Gritsamada.
• Mandala 3: Vishvamitra.
• Mandala 4: Vamadeva.
• Mandala 5: Atri.
• Mandala 6: Bharadvaja.
• Mandala 7: Vasishtha.

Why not the other options?

• ✗Mandala 1 and Mandala 10 are later collections from different sages.
• ✗Mandala 7 is the book of the Vasishtha family.