In His small form, Krsna was kind enough to show His mother the virat-rupa, the universal form, so that she could enjoy seeing what kind of child she had on her lap

Expressions researched:
"In His small form, Kṛṣṇa was kind enough to show His mother the virāṭ-rūpa, the universal form, so that she could enjoy seeing what kind of child she had on her lap"

Srimad-Bhagavatam

SB Canto 10.1 to 10.13

By the arrangement of yogamāyā, Kṛṣṇa's pastimes with mother Yaśodā were all regarded as ordinary. So here was an opportunity for Kṛṣṇa to show His mother that the whole universe is situated within Him. In His small form, Kṛṣṇa was kind enough to show His mother the virāṭ-rūpa, the universal form, so that she could enjoy seeing what kind of child she had on her lap.

SB 10.7.35-36, Translation and Purport

O King Parīkṣit, when the child Kṛṣṇa was almost finished drinking His mother's milk and mother Yaśodā was touching Him and looking at His beautiful, brilliantly smiling face, the baby yawned, and mother Yaśodā saw in His mouth the whole sky, the higher planetary system and the earth, the luminaries in all directions, the sun, the moon, fire, air, the seas, islands, mountains, rivers, forests, and all kinds of living entities, moving and nonmoving.

By the arrangement of yogamāyā, Kṛṣṇa's pastimes with mother Yaśodā were all regarded as ordinary. So here was an opportunity for Kṛṣṇa to show His mother that the whole universe is situated within Him. In His small form, Kṛṣṇa was kind enough to show His mother the virāṭ-rūpa, the universal form, so that she could enjoy seeing what kind of child she had on her lap. The rivers have been mentioned here as the daughters of the mountains (nagāṁs tad-duhitṟḥ). It is the flowing of the rivers that makes big forests possible. There are living entities everywhere, some of them moving and some of them not moving. No place is vacant. This is a special feature of God's creation.