Manava Dharmashastra 4.23

4.23

yadā'yaṃ puruṣa ucchvasiti tadaivamananena dhyātavyam 'vācaṃ prāṇe juhomīti' | bhāṣamāṇena ca 'vāci prāṇaṃ juhomīti' | etāvataiva pañcayajñā nirvṛttā bhavanti | "yadi nityāḥ phalāya na vaktavyāḥ" | ātmajñāścātrādhikriyante | vihito hyayamarthaḥ pañcāgnyupāsanāyāṃ upaniṣatsu kauṣītakībrāhmaṇe vistareṇa | akṣayaṃ phalataḥ, apunarāvṛttiphalatvāt |

Some people constantly offer their life-breath into speech, and their speech into the life-breath,—knowing that in speech and in life-breath rests the imperishable fulfilment of sacrifices.—(23)

Medhātithi’s commentary (manubhāṣya):
Whenever a man breathes, he should think—‘I am offering speech into Life-breath;’ and when he speaks, he should think—‘I am offering Life-breath into Speech.’ By this alone the Five Sacrifices become accomplished.

“If these are obligatory, they should not be spoken of as leading to any results.”

As a matter of fact, only such persons are entitled to this form of sacrifice as are cognisant of the real nature of the Soul.

This same fact has been laid down in the Upṇniṣads, in connection with ‘the worship of the Five Fires,’ and in great detail in the Kauṣitaki Brāhmaṇa.

‘Imperishable’—in their results; their results consisting in non-return to the cycle of birth and rebirth.—(23)