Śrīmad-Bhāgavatam · Text 10.46.31
Who is speaking and story frame
एतौ हि विश्वस्य च बीजयोनी
रामो मुकुन्द: पुरुष: प्रधानम् ।
अन्वीय भूतेषु विलक्षणस्य
ज्ञानस्य चेशात इमौ पुराणौ ॥ ३१ ॥
etau hi viśvasya ca bīja-yonī
rāmo mukundaḥ puruṣaḥ pradhānam
anvīya bhūteṣu vilakṣaṇasya
jñānasya ceśāta imau purāṇau
These two Lords, Mukunda and Balarāma, are each the seed and womb of the universe, the creator and His creative potency. They enter the hearts of living beings and control their conditioned awareness. They are the primeval Supreme.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.