Bhagavatapurana 10.46.31

10.46.31

etau hi viśvasya ca bīja-yonī rāmo mukundaḥ puruṣaḥ pradhānam /
anvīya bhūteṣu vilakṣaṇasya jñānasya ceśāta imau purāṇau //

31. “For these two indeed are the First Causes (the efficient and material) of the Universe, Balarama and Mukunda, being the Purusha and Matter: having entered into all beings, the two Ancient Lords rule the Jiva (the intelligent Being) distinguished in various ways and by points of difference.