Shatapatha Brahmana 4.5.8.13

4.5.8.13

dvau vonnetārau kurvīta | tayoryataro nāśrāvayettasmā enāṃ dadyādvyṛddho vā eṣa unnetā ya ṛtvikṣannāśrāvayati vyṛddho eṣā virāḍyā vivṛḍhā tadvyṛddha evaitadvyṛddhaṃ dadhāti

Or let him appoint two Unnetris, and let him give her to him, of the two, who does not call for the Sraushat; for defective, indeed, is he who, being an officiating priest, does not call for the Sraushat; and defective also is the Virâg which is pulled asunder: thus he puts the defective to the defective.