SB 10.11.6
ulukhalam vikarsantam
damna baddham svam atmajam
vilokya nandah prahasad-
vadano vimumoca ha
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When Nanda Maharaja saw his own son bound with ropes to the wooden mortar and dragging it, he smiled and released Krsna from His bonds.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Nanda Maharaja was surprised that Yasoda, Krsna’s mother, could have bound her beloved child in such a way. Krsna was exchanging love with her. How then could she have been so cruel as to bind Him to the wooden mortar? Nanda Maharaja understood this exchange of love, and therefore he smiled and released Krsna. In other words, as Krsna, the Supreme Personality of Godhead, binds a living entity in fruitive activities, He binds mother Yasoda and Nanda Maharaja in parental affection. This is His pastime.