The Rikas, the Yagumshi, and the Samani form eight syllables. One foot (the second) of the Gayatri consists of eight syllables. This (one foot) of it is that (i.e. the three Vedas, the Rig-veda, Yagur-veda, and Sama-veda). And he who thus knows that foot of it, conquers as far as that threefold knowledge extends.

In plain words: The names of the three Vedas, the oldest holy books, together make eight syllables, like the second line of the Gayatri. Whoever knows this line as the three Vedas gains all that this sacred knowledge reaches.