CC Madhya 23.68
kāntiḥ sammohinī parā
devī — who shines brilliantly; kṛṣṇa-mayī — nondifferent from Lord Kṛṣṇa; proktā — called; rādhikā — Śrīmatī Rādhārāṇī; para-devatā — most worshipable; sarva-lakṣmī-mayī — presiding over all the goddesses of fortune; sarva-kāntiḥ — in whom all splendor exists; sammohinī — whose character completely bewilders Lord Kṛṣṇa; parā — the superior energy.
“ ‘The transcendental goddess Śrīmatī Rādhārāṇī is the direct counterpart of Lord Śrī Kṛṣṇa. She is the central figure for all the goddesses of fortune. She possesses all the attraction to attract the all-attractive Personality of Godhead. She is the primeval internal potency of the Lord.’
This text is found in the Bṛhad-gautamīya-tantra. For an explanation, see Ādi-līlā 4.83-95.