Śrīmad-Bhāgavatam · Text 3.2.11
Who is speaking and story frame
प्रदर्श्यातप्ततपसामवितृप्तदृशां नृणाम् ।
आदायान्तरधाद्यस्तु स्वबिम्बं लोकलोचनम् ॥ ११ ॥
pradarśyātapta-tapasām
avitṛpta-dṛśāṁ nṛṇām
ādāyāntar adhād yas tu
sva-bimbaṁ loka-locanam
Lord Śrī Kṛṣṇa, who manifested His eternal form before the vision of all on the earth, performed His disappearance by removing His form from the sight of those who were unable to see Him [as He is] due to not executing required penance.
Read Śrīla Prabhupāda's purport on Vedabase.io