The Guruvar Vrat Mantra is chanted during the observance of the Thursday fast (Guruvar Upavasa), dedicated to Brihaspati (Guru), the planetary deity of Jupiter and the preceptor of the gods. This practice is rooted in Puranic traditions, such as the *Bhavishya Purana* (Chapter on Vratas), which extols the fast for removing obstacles and bestowing wisdom. The mantra typically includes the beej-akshara 'Grum' (ग्रुं), representing the essence of Jupiter's energy, as described in *Mantra Mahodadhi* (Chapter 7, on Graha Mantras).
The primary mantra, 'Om Gurave Namah', is a simple salutation to the divine teacher, while the Brihaspati Gayatri ('Om Brihaspataye Vidmahe, Divyadevaya Dhimahi, Tanno Guru Prachodayat') is also recited for deeper meditation. The fast is observed on Thursdays, from sunrise to the next sunrise, with a single meal of satvik food. Chanting is recommended 108 times (one mala) during the morning after bathing, facing east, using a yellow rosary (associated with Jupiter).
The purpose includes gaining wisdom, prosperity, marital harmony, and the blessings of one's guru. According to *Jyotisha texts*, propitiating Jupiter through this vrat mitigates the malefic effects of a weak Guru in the birth chart and enhances knowledge and fortune. Cautions: The fast should be undertaken with a pure mind and body; those with health issues may modify the fast as per tradition.
The mantra is considered safe for all, but consistent practice is emphasized over mere ritual. The *Devi Mahatmya* (though primarily Devi-focused) also references the importance of planetary worship for worldly success, aligning with this vrat's goals.
Salutations to the divine teacher (Guru).
The mantra includes the beej-akshara 'Grum' (ग्रुं) in some forms, representing Jupiter's essence.