Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 7.7.2

7.7.2

tatho eva etad yajamānaḥ prāyaṇīyena eva prāṇam āpnoty udayanīyena udānam / (soma: prāyaṇīyeṣṭi)

In this very way the sacrificer by the opening offering obtains out-breath, [and] by the concluding offering, in-breath.