Jaiminīya (Talavakāra) Brāhmaṇa 1.168

When the Aṅgirases were performing a sacrificial session, grit arose in their eyes. / They desired: 'May we not be blind; may we see clearly.' / They applied to their eyes this dark caru for Soma. / They applied it with this mantra: / 'With which the surveyor of men won the race, with which [he made] the falcon, the bird of fair wings, / That unlimited eye which they call Aditi—may Soma, the surveyor of men, bestow that in me.' / Then indeed they became unblind; they saw clearly. / He indeed becomes unblind, he sees clearly, who knows thus. / Concerning this they say: 'Is it to be eaten or not to be eaten?' If one is learned in the scriptures but has lost fame, he should eat it. / For the learned in the scriptures are here fit for fame. / He who is learned in the scriptures and becomes stripped of fame—his fame has gone to that world. By this it is brought back again when he eats this dark caru for Soma. / But about this Śāṭyāyani said: 'It should not be eaten at all. Who would fetch fame from there, where he will dwell for more nights?' / Therefore one should not eat it at all.

'At every sacrifice, to Fire, for you…'

This is a fourth part of the sāman.

Thereby they establish the sacrifice in the sāman.

This is the body of the sāmans.