PRAŚNA UPANISHAD · 1.4

तस्मै स होवाच प्रजाकामो वै प्रजापतिः स तपोऽतप्यत
स तपस्तप्त्वा स मिथुनमुत्पादयते । रयिं च प्राणं
चेत्येतौ मे बहुधा प्रजाः करिष्यत इति ॥ १.४॥

tasmai sa hovāca prajākāmo vai prajāpatiḥ sa tapo’tapyata
sa tapastaptvā sa mithunamutpādayate । rayiṃ ca prāṇaṃ
cetyetau me bahudhā prajāḥ kariṣyata iti ॥ 1.4॥

To him answered the Rishi Pippalada: “The Eternal Father desired children, therefore he put forth his energy and by the heat of his energy produced twin creatures, Prana the Life, who is Male, and Rayi the Matter, who is Female. ‘These’ said he ‘shall make for me children of many natures.’

Sri Aurobindo · CWSA 18, p. 176