CC Ādi 5.140

keyaṁ vā kuta āyātā
daivī vā nāry utāsurī
prāyo māyāstu me bhartur
nānyā me ’pi vimohinī
Synonyms: 
— who; iyam — this; — or; kutaḥ — from where; āyātā — has come; daivī — whether demigod; — or; nārī — woman; uta — or; āsurī — demoness; prāyaḥ — in most cases; māyā — illusory energy; astu — she must be; me — My; bhartuḥ — of the master, Lord Kṛṣṇa; na — not; anyā — any other; me — My; api — certainly; vimohinī — bewilderer.
Translation: 
“Who is this mystic power, and where has she come from? Is she a demigod or a demoness? She must be the illusory energy of My master, Lord Kṛṣṇa, for who else can bewilder Me?”
Purport: 

The playful pastimes of the Lord caused suspicion in the mind of Lord Brahmā, and therefore Lord Brahmā, to test Kṛṣṇa’s Lordship, stole all the Lord’s calves and cowherd boys with his own mystic power. Śrī Kṛṣṇa responded, however, by replacing all the calves and boys in the field. Lord Balarāma’s thoughts of astonishment at such wonderful retaliation are recorded in this verse (Bhāg. 10.13.37).