SB 2.7.30
grhnita yad yad upabandham amusya mata
sulbam sutasya na tu tat tad amusya mati
yaj jrmbhato ’sya vadane bhuvanani gopi
samviksya sankita-manah pratibodhitasit
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When the cowherd woman [Krsna’s foster mother, Yasoda] was trying to tie the hands of her son with ropes, she found the rope to be always insufficient in length, and when she finally gave up, Lord Krsna, by and by, opened His mouth, wherein the mother found all the universes situated. Seeing this, she was doubtful in her mind, but she was convinced in a different manner of the mystic nature of her son.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
One day Lord Krsna as the naughty child disturbed His mother Yasoda, and she began to tie up the child with ropes just to punish Him. But no matter how much rope she used, she found it always insufficient. Thus she became fatigued, but in the meantime the Lord opened His mouth, and the affectionate mother saw within the mouth of her son all the universes situated together. The mother was astonished, but out of her deep affection for Krsna she thought that the Almighty Godhead Narayana had kindly looked after her son just to protect Him from all the continuous calamities happening to Him. Because of her deep affection for Krsna, she could never think that her very son was Narayana, the Personality of Godhead Himself. That is the action of yoga-maya, the internal potency of the Supreme Lord, which acts to perfect all the pastimes of the Lord with His different types of devotees. Who could play such wonders without being God?