gayatri is the veda mantra to be recited at sandhya periods
gayatri means "A mantra that protects those who recite it"
gayatri is considered as the mother of all mantras and is said to be
equivalent to vedas. One can improve his tejas, physical and mental
strength by reciting it. This mantra has the power to ward of all
sins.
Tatsavitur vareniya - Bhargo devasya dhimahi - dhiyo yo nah
prachodayat is the gayatri mantra. Om (Pranava) and Bhur Bhuvasuvah (Vyahrithi)
are prefixed.