Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 26
Sanskrit:
कालेनाल्पेन राजर्षे राम: कृष्णश्च गोकुले ।अघृष्टजानुभि: पद्भिर्विचक्रमतुरञ्जसा ॥ २६ ॥
ITRANS:
kālenālpena rājarṣerāmaḥ kṛṣṇaś ca gokuleaghṛṣṭa-jānubhiḥ padbhirvicakramatur añjasā
Translation:
O King Parīkṣit, within a very short time both Rāma and Kṛṣṇa began to walk very easily in Gokula on Their legs, by Their own strength, without the need to crawl.
Purport:
Instead of crawling with Their knees, the babies could now stand up by holding on to something and walk little by little, without difficulty, by the strength of Their legs.