Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 29

Sanskrit:

तयोरित्थं भगवति कृष्णे नन्दयशोदयो: ।वीक्ष्यानुरागं परमं नन्दमाहोद्धवो मुदा ॥ २९ ॥

ITRANS:

tayor itthaṁ bhagavatikṛṣṇe nanda-yaśodayoḥvīkṣyānurāgaṁ paramaṁnandam āhoddhavo mudā

Translation:

Uddhava then joyfully addressed Nanda Mahārāja, having clearly seen the supreme loving attraction he and Yaśodā felt for Kṛṣṇa, the Supreme Personality of Godhead.

Purport:

If Uddhava had seen Nanda and Yaśodā actually suffering, he would not have reacted with joy. But in fact all emotions on the spiritual platform are transcendental bliss. The so-called anguish of the pure devotees is another form of loving ecstasy. This was clearly seen by Uddhava, and thus he spoke as follows.