The Lord appeared as the Hayagrīva incarnation in a sacrifice performed by me [Brahmā]. He is the personified sacrifices, and the hue of His body is golden. He is the personified Vedas as well, and the Supersoul of all demigods. When He breathed, all the sweet sounds of the Vedic hymns came out of His nostrils.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सत्रे ममास भगवान् हयशीरषाथो साक्षात्स यज्ञपुरुषस्तपनीयवर्णः । छन्दोमयो मखमयोऽखिलदेवताऽऽत्मा वाचो बभूवुरुशतीः श्वसतोऽस्य नस्तः
satre mamāsa bhagavān hayaśīraṣātho sākṣātsa yajñapuruṣastapanīyavarṇaḥ | chandomayo makhamayo'khiladevatā''tmā vāco babhūvuruśatīḥ śvasato'sya nastaḥ
SB 2.7.11