GVY: Text Seven

saptasyasan paridhayaha
trissapta samidhah kritaha
deva yadjajnam tanvanaha.

abadhnan purusham pashumFor this (yajna or spiritual ceremony) there were seven paridhis (fuel pieces serving as borders). And, twenty-one items were made the samit or sacrificial fuel sticks. When the devas were performing this yajna or ceremony, they tied the purusha (himself) as the pashu (sacrificial animal).