CC Adi-lila 04.215 - Padma Purana
Sri Caitanya-caritamrta
CC Adi-lila
CC Adi 4.215, Translation and Purport:
"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."
This verse is from the Padma Purāṇa.