SB 10.10.39

śrī-śuka uvāca
itthaṁ saṅkīrtitas tābhyāṁ
 bhagavān gokuleśvaraḥ
dāmnā colūkhale baddhaḥ
 prahasann āha guhyakau
Synonyms: 
śrī-śukaḥ uvāca — Śrī Śukadeva Gosvāmī continued to speak; ittham — in this way, as aforesaid; saṅkīrtitaḥ — being glorified and praised; tābhyām — by the two young demigods; bhagavān — the Supreme Personality of Godhead; gokula-īśvaraḥ — the master of Gokula (because He is sarva-loka-maheśvara); dāmnā — by the rope; ca — also; ulūkhale — on the wooden mortar; baddhaḥ — bound; prahasan — smiling; āha — said; guhyakau — unto the two young demigods.
Translation: 
Śukadeva Gosvāmī continued: The two young demigods thus offered prayers to the Supreme Personality of Godhead. Although Śrī Kṛṣṇa, the Supreme Godhead, is the master of all and was certainly Gokuleśvara, the master of Gokula, He was bound to the wooden mortar by the ropes of the gopīs, and therefore, smiling widely, He spoke to the sons of Kuvera the following words.
Purport: 

Kṛṣṇa was smiling because He was thinking to Himself, “These two young demigods fell from the higher planetary system to this planet, and I have delivered them from the bondage of standing for a long time as trees, but as for Me, I am bound by the ropes of the gopīs and am subject to their chastisements.” In other words, Kṛṣṇa submits to being chastised and bound by the gopīs because of pure love and affection worthy of being praised by a devotee in so many ways.