[Advaita-l] tricha on agni

[Gopal]

Namaste,

In his commentary on Rig Veda, Wilson mentions about a tricha (three rik
mantras in tandem) to be recited during equinox. This is mentioned for the
mantra starting 'agnir murdha..' 1.59.2'.  I do not see any note on this in
Sayana's bhashya or in relation to other tricha like  recommended for surya
namaskara. Could anyone provide any information about the three rik mantras
that are associated with equinox with respect to agni vaishvanara?

thanks
..gopal gopinath