CC Ādi 4.215

yathā rādhā priyā viṣṇos
tasyāḥ kuṇḍaṁ priyaṁ tathā
sarva-gopīṣu saivaikā
viṣṇor atyanta-vallabhā
Synonyms: 
yathā — just as; rādhā — Śrīmatī Rādhārāṇī; priyā — very dear; viṣṇoḥ — to Lord Kṛṣṇa; tasyāḥ — Her; kuṇḍam — bathing place; priyam — very dear; tathā — so also; sarva-gopīṣu — among all the gopīs; — She; eva — certainly; ekā — alone; viṣṇoḥ — of Lord Kṛṣṇa; atyanta-vallabhā — most dear.
Translation: 
“Just as Rādhā is dear to Lord Kṛsṇa, so Her bathing place [Rādhā-kuṇḍa] is dear to Him. She alone is His most beloved of all the gopīs.”
Purport: 

This verse is from the Padma Purāṇa.