Shatapatha Brahmana 9.5.1.20

9.5.1.20

teṣu preteṣu | prāyaṇīyam niravapaṃstadu hāsurā anveva bubudhire tasya śamyoruktamāsāthājagmustasmātsa yajñaḥ śamyvantaste devā asurānpratidṛśya mamullupya yajñamanyadeva kartuṃ dadhrire 'nyadvai kurvantīti punareva preyuḥ

When they had gone away, they (the gods) prepared the Opening-offering. But the Asuras became aware of this also. The Samyos (formula) of that (offering) had been pronounced, when they arrived; whence that sacrifice ends with the Samyos. The gods, espying the Asuras, snatched up the sacrifice, and began doing something else. They went away again, thinking, 'It is something else they are doing.'