Shatapatha Brahmana 11.4.4.12

11.4.4.12

atha yadi manyeta sampannam me yajñe'bhūditi svargyam ma etatsvargaloko bhaviṣyāmītyeva tadupāsīta saiṣā yajñasya samṛddhiḥ sa yo haivametāṃ yajñasya samṛddhiṃ veda sarvasamṛddhena haivāsya yajñeneṣṭam bhavati

And if he think, 'There has been that which was perfect in my sacrifice,' let him believe, 'That is conducive to heaven for me: I shall become one of those in the heavenly world.' This then is the successful issue of the sacrifice; and, verily, whosoever thus knows this to be the successful issue of the sacrifice, by him offering is made by a wholly successful sacrifice.