CC Adi-lila 03.104 - Gautamiya-tantra
Sri Caitanya-caritamrta
CC Adi-lila
CC Adi 3.104, Translation and Purport:
"Śrī Kṛṣṇa, who is very affectionate toward His devotees, sells Himself to a devotee who offers Him merely a tulasī leaf and a palmful of water."
This is a verse from the Gautamīya-tantra.