CC Madhya 20.175
dvibhuja-svarūpa kabhu, kabhu haya caturbhuja
“An example of vaibhava-prakāśa is the son of Devakī. He sometimes has two hands and sometimes four hands.
When Lord Kṛṣṇa took His birth, He appeared outside the womb as four-handed Viṣṇu. Then Devakī and Vasudeva offered their prayers to Him and asked Him to assume His two-handed form. The Lord immediately assumed His two-handed form and ordered that He be transferred to Gokula, on the other side of the river Yamunā.