Shatapatha Brahmana 1.2.2.9

1.2.2.9

taṃ na satrā pṛthu kuryāt | mānuṣaṃ ha kuryādyatpṛthuṃ kuryādvyṛddhaṃ vai tadyajñasya yanmānuṣaṃ nedvyṛddhaṃ yajño karavāṇīti tasmānna satrā pṛthuṃ kuryāt

Let him not make it too broad; for he would make it a human (profane, common cake), if he were to make it (too) broad. Unlucky for (or, excluded from) the sacrifice indeed is that one, to wit, the common (cake). 'That I may not do anything that is unlucky at the sacrifice,' thus (he thinks, and) for that reason he should not make it too broad.