Because of its wonderful transcendental qualities, Radha-kunda is as dear to Krsna as Srimati Radharani. It was in that lake that the all-opulent Lord Sri Krsna performed His pastimes with Srimati Radharani with great pleasure and transcendental bliss

Expressions researched:
"Because of its wonderful transcendental qualities, Rādhā-kuṇḍa is as dear to Kṛṣṇa as Śrīmatī Rādhārāṇī. It was in that lake that the all-opulent Lord Śrī Kṛṣṇa performed His pastimes with Śrīmatī Rādhārāṇī with great pleasure and transcendental bliss"

Sri Caitanya-caritamrta

CC Madhya-lila

“‘Because of its wonderful transcendental qualities, Rādhā-kuṇḍa is as dear to Kṛṣṇa as Śrīmatī Rādhārāṇī. It was in that lake that the all-opulent Lord Śrī Kṛṣṇa performed His pastimes with Śrīmatī Rādhārāṇī with great pleasure and transcendental bliss. Whoever bathes just once in Rādhā-kuṇḍa attains Śrīmatī Rādhārāṇī’s loving attraction for Śrī Kṛṣṇa. Who within this world can describe the glories and sweetness of Śrī Rādhā-kuṇḍa?’”.

CC Madhya 18.12, Translation and Purport

“‘Because of its wonderful transcendental qualities, Rādhā-kuṇḍa is as dear to Kṛṣṇa as Śrīmatī Rādhārāṇī. It was in that lake that the all-opulent Lord Śrī Kṛṣṇa performed His pastimes with Śrīmatī Rādhārāṇī with great pleasure and transcendental bliss. Whoever bathes just once in Rādhā-kuṇḍa attains Śrīmatī Rādhārāṇī’s loving attraction for Śrī Kṛṣṇa. Who within this world can describe the glories and sweetness of Śrī Rādhā-kuṇḍa?’”

This verse is found in the Govinda-līlāmṛta (7.102).