Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 4.10.8

4.10.8

api vā agnihotrīm eva navān ādayitvā tasyai dugdhena sāyam prātar agnihotram juhuyād ubhayasya āptyai / (Vikṛti iṣṭayah)

Or having fed the Agnihotra cow with the new [grains], he should offer the Agnihotra evening and morning with her milk, for the attainment of both.