CC Ādi 4.187
tāhā haite koṭi-guṇa gopī āsvādaya
The gopīs taste a pleasure ten million times greater than the pleasure Lord Kṛṣṇa derives from seeing them.
The wonderful characteristics of the gopīs are beyond imagination. They have no desire for personal satisfaction, yet when Kṛṣṇa is happy by seeing them, that happiness of Kṛṣṇa makes the gopīs a million times more happy than Kṛṣṇa Himself.