Rudra-prasava-varṇana
The Manifestation and Naming of Rudra / Nīlalohita
भवस्य या द्वितीया तु आपो नाम्ना तनुः स्मृता / तस्या धात्री स्मृता पत्नी पुत्रश्च उशना स्मृतः
bhavasya yā dvitīyā tu āpo nāmnā tanuḥ smṛtā / tasyā dhātrī smṛtā patnī putraśca uśanā smṛtaḥ
Bhava’s second manifestation is remembered as Āpaḥ, the Waters. Her consort is Dhātrī, and his son is recalled as Uśanā.