Bhagavatapurana 8.18.12

8.18.12

yat tadvapurbhāti vibhūṣaṇāyudhair avyaktacidvyaktamadhārayaddhariḥ /
babhūva tenaiva sa vāmano vaṭuḥ sampaśyatordivyagatiryathā naṭaḥ //

12. While Aditi and Kasyapa were witnessing, Sri Hari changed that very form which He first manifested to them (by means of His glorious lustre), with ornaments and weapons, and like an actor of wonderful powers became a boy-Brahmacharin.