Verse 11.5.8.6

sa hovāca yadyṛkto bhūriti caturgṛhītamājyaṃ gṛhītvā gārhapatye juhavatha yadi yajuṣṭo bhuva iti caturgṛhītamājyaṃ gṛhītvāgnīdhrīye juhavathānvāhāryapacane vā haviryajñe yadi sāmataḥ svariti caturgṛhītamājyaṃ gṛhītvāhavanīye juhavatha yadyu avijñātamasatsarvāṇyanudrutyāhavanīye juhavatha tadṛgvedenaivargvedam bhiṣajyati yajurvedena yajurvedaṃ sāmavedena sāmavedaṃ sa yathā parvaṇā parva saṃdadhyādevaṃ haiva sa saṃdadhāti ya etābhirbhiṣajyatyatha yo hāto'nyena bhiṣajyati yathā śīrṇena śīrṇaṃ saṃdhitsedyathā vā śīrṇe garamabhinidadhyādevaṃ tattasmādevaṃvidameva brahmāṇaṃ kurvīta nānevaṃvidam

Preview of English translation:

6. He spake, ‘If (it were to fail) in respect of the Ric, ye should take ghee by four ladlings and offer it in the Garhapatya fire with 'Bhuh!' and if in respect of the Yajus, ye should take ghee by four ladlings and offer it in the Agnidhriya—or in the Anvaharyapacana in the case of a Haviryajna—with 'Bhuvah!' and if in respect of the Saman, ye should take ghee by four ladlings and offer it in the Ahavaniya with 'Svar!' But if it should not be known (where the mistake has occurred), ye should make offering in the Ahavaniya after uttering rapidly all (the three sacred words): thus one heals the Rig-veda by the Rig-veda, the Yajur-veda by the Yajur-veda, and the Sama-veda by the Sama-veda;—even as one would put together joint with joint, so does he put together (the broken part of the sacrifice) whoever heals it by means of these (three sacred words). But if he heals it in any other way than this, it would be just as if one tried to put together something that is broken with something else that is broken, or as if one were to apply some poison as lotion to a broken part. Let him therefore appoint only one who knows this (to officiate as) his Brahman, and not one who does not know this.

For a detailled translation, including proper diacritics and footnotes, go the full English translation.