There is a mantra called the Gayatri mantra, which is considered the most powerful.
It is said that Hindus receive a sacred object from a guru through an initiation ceremony, and they receive it with reverence and quietly chant it.
The version that is famous is the one by Sai Baba. It seems there are various variations in terms of tempo and intonation.
ॐ भूर्भुवः॒ स्वः । |
oṃ bhūr bhuvaḥ svaḥ |
Tat savitur varenyam. |
tat savitur vareṇyaṃ |
Bhargo devasya dhimahi. |
bhargo devasya dhīmahi. |
May that intellect inspire us. |
May [the goddess] Saraswati enlighten our intellect. |
Another version.