The deployment of bR^ihat and rathantara

Source: here.

The ancient bhArgava ushanA kAvya has declared how the bR^ihat and rathantara are to be deployed for attacking the bhrAtR^ivya-s. When dispatched the two sAmans assumes the form of a chakra of brahman and proceed to slay the foe even as the deva-s had imbued a chakra with the force of indra’s vajra to overthrow the dAnavas. At the same time it protects the yajamAna.
The ritualist first sings the rathantara and makes a soma offering to indra who is glorified by the sAman. Then he utters the formula ” namo mAtre pR^ithivyai rathantara mA mA hiMsIH ||”
Then he sings the bR^ihat and offers soma and utters the mantra: ” divaM pitaraM upashraye bR^ihan mA mA hiMsIH ||”
Then he recites both and utters the deadly formula: “prANair amuShya prANAn vR^i~NkShva |
takShena takShaNIyasAyur asya prANAn vR^i~NkShva | kruddha enaM manunyA daNDena jahi | dhanur enaM AtatyeShvA vidhya ||”
With that the brahman of the sAmans issues forth as a deadly astra in pursuit of the foe. The jaiminIya declares “bR^ihad-rathantarayor evainaM mukhe .apidadhAti | yaM dveShTi taM purA saMvatsarAt prANo jahAti |”