Śrīmad-Bhāgavatam · Text 10.2.20
Who is speaking and story frame
तां वीक्ष्य कंस: प्रभयाजितान्तरांविरोचयन्तीं भवनं शुचिस्मिताम् । आहैष मे प्राणहरो हरिर्गुहांध्रुवं श्रितो यन्न पुरेयमीदृशी ॥ २० ॥
tāṁ vīkṣya kaṁsaḥ prabhayājitāntarāṁ
virocayantīṁ bhavanaṁ śuci-smitām
āhaiṣa me prāṇa-haro harir guhāṁ
dhruvaṁ śrito yan na pureyam īdṛśī
Because the Supreme Personality of Godhead was within her womb, Devakī illuminated the entire atmosphere in the place where she was confined. Seeing her jubilant, pure and smiling, Kaṁsa thought, “The Supreme Personality of Godhead, Viṣṇu, who is now within her, will kill me. Devakī has never before looked so brilliant and jubilant.”
Read Śrīla Prabhupāda's purport on Vedabase.io